JP5835985B2 - Plasma processing apparatus and plasma processing method - Google Patents

Plasma processing apparatus and plasma processing method Download PDF

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JP5835985B2
JP5835985B2 JP2011163750A JP2011163750A JP5835985B2 JP 5835985 B2 JP5835985 B2 JP 5835985B2 JP 2011163750 A JP2011163750 A JP 2011163750A JP 2011163750 A JP2011163750 A JP 2011163750A JP 5835985 B2 JP5835985 B2 JP 5835985B2
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plasma
processing
processing container
extended protrusion
electrode
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JP2012084848A (en
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太一 門田
太一 門田
北川 淳一
淳一 北川
山下 潤
潤 山下
中村 秀雄
秀雄 中村
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東京エレクトロン株式会社
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32Gas-filled discharge tubes, e.g. for surface treatment of objects such as coating, plating, etching, sterilising or bringing about chemical reactions
    • H01J37/32009Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32192Microwave generated discharge

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method for performing plasma processing on an object to be processed such as a semiconductor wafer.

  In the manufacturing process of a semiconductor device, various processes such as etching, ashing, and film formation are performed on a semiconductor wafer that is an object to be processed. For these processes, a plasma processing apparatus is used that performs plasma processing on a semiconductor wafer in a processing container that can be maintained in a vacuum atmosphere.

  In recent years, semiconductor wafers are becoming larger and devices are becoming finer. Correspondingly, the efficiency of plasma processing (for example, film formation rate) and uniformity of processing within the wafer surface are improved. Is required. For this purpose, there is a method in which an electrode is embedded in a mounting table for mounting a semiconductor wafer in a processing vessel of a plasma processing apparatus, high frequency power is supplied to the electrode, and plasma processing is performed while applying a bias voltage to the semiconductor wafer. It is attracting attention (for example, Patent Document 1).

  When high-frequency power is supplied to the electrode of the mounting table, a conductive member having a ground potential that is disposed across the plasma generation space with respect to the electrode embedded in the mounting table serves as a counter electrode. That is, when bias high-frequency power is supplied to the electrode in the mounting table, the bias returns from the mounting table to the counter electrode via plasma, and from the counter electrode to the ground of the bias high-frequency power source via the wall of the processing vessel. A high-frequency current path (RF return circuit) is formed. When such a high-frequency current path is not stably formed, the oscillation width of the potential (Vp) of the plasma generated in the processing container becomes large, and stable plasma processing becomes difficult. In addition, when the oscillation width of the plasma potential is large, the surface of the counter electrode, which is usually formed of aluminum or the like, is sputtered by the action of plasma, particularly in processing at a low pressure of several tens of Pa or less, resulting in contamination. is there. In order to suppress the oscillation of the plasma potential, it is necessary to ensure a sufficient area of the counter electrode. However, in the conventional microwave plasma processing apparatus such as Patent Document 1, since the microwave transmission plate is disposed on the upper part of the processing container, the area of the counter electrode is sufficiently different from the plasma processing apparatus such as the parallel plate type. There are restrictions on the device configuration.

  For this reason, in the microwave plasma processing apparatus, a plasma processing apparatus is proposed in which an annular counter electrode made of silicon or aluminum is detachably provided on the periphery of the microwave transmission plate inside the processing container. (For example, Patent Documents 2 and 3). In the prior arts of these Patent Documents 2 and 3, the plasma potential (Vp) when supplying high-frequency power to the mounting table can be stabilized by sufficiently securing the area of the counter electrode. However, since the counter electrodes of Patent Documents 2 and 3 are arranged in close contact with the microwave transmission plate, the effective area for introducing the microwave is narrowed, and the introduction of the microwave itself becomes unstable, and the processing container There is a possibility that plasma is not stably generated in the inside. In the microwave plasma processing apparatus, since plasma is generated immediately below the microwave transmission plate, the electron temperature is highest in a region near the microwave transmission plate. Therefore, when the counter electrode is brought into close contact with the microwave transmission plate and protruded into the processing space as in Patent Documents 2 and 3, the tip of the counter electrode is easily scraped by the plasma, and there is a concern about the occurrence of contamination. The

International Publication WO2009 / 123198 A1 Japanese Patent Laid-Open No. 9-266095 Japanese Patent Laid-Open No. 10-214823

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plasma potential in a plasma processing apparatus that supplies high-frequency power for bias to an electrode of a mounting table on which an object to be processed is mounted. It is to suppress vibrations, generate stable plasma, and prevent contamination due to sputtering of a metal counter electrode.

  The plasma processing apparatus of the present invention includes a processing container having an open upper part for processing a target object using plasma, a mounting table for mounting the target object in the processing container, and a table embedded in the mounting table. A first electrode for applying a bias voltage to the processing body; a dielectric plate for blocking the opening of the processing container to define a plasma generation space and transmitting microwaves into the processing container; and A planar antenna provided above the dielectric plate and introducing the microwave generated by the microwave generator into the processing container via the dielectric plate and an upper part of the processing container, forming an annular shape And a lid member that protrudes toward the plasma generation space on the inner peripheral side thereof, and a lid member that supports the outer peripheral portion of the dielectric plate on the upper surface of the corresponding contact support portion, and the processing container or the From the contact support At least a portion of the second electrode protruding toward the plasma generation space in the processing container with a gap between the dielectric plate and paired with the first electrode across the plasma generation space And a space formed between the upper surface of the extended protrusion and the lower surface of the dielectric plate.

  In the plasma processing apparatus of the present invention, the distance between the upper surface of the extended protrusion and the lower surface of the dielectric plate is preferably in the range of 10 mm to 30 mm.

  Moreover, in the plasma processing apparatus of the present invention, it is preferable that the extended protrusion is provided with a protrusion whose tip does not reach above the end of the object to be processed placed on the mounting table.

  In the plasma processing apparatus of the present invention, it is preferable that a gas introduction port for introducing a processing gas is provided in a space between the dielectric plate and the extended protrusion.

  In the plasma processing apparatus of the present invention, the extended protrusion may be formed integrally with the lid member, or the extended protrusion may be formed integrally with the processing container. . Further, the extended protrusion may be an auxiliary electrode member fixed to the lid member or an auxiliary electrode member fixed to the processing container.

  In the plasma processing apparatus of the present invention, it is preferable that irregularities are provided on the surface of the extended protrusion.

  In the plasma processing apparatus of the present invention, the surface area of the second electrode facing the plasma generation space is in the range of 1 to 5 with respect to the area of the buried region of the first electrode in the mounting table. Preferably there is.

  Moreover, it is preferable that the plasma processing apparatus of this invention is further equipped with the protective film on the surface of the said expansion protrusion part. In this case, the protective film is preferably made of silicon.

  Moreover, it is preferable that the plasma processing apparatus of this invention is further equipped with the insulating board along the inner wall of the said processing container of the position lower than the height of the mounting surface of the said mounting base at least. In this case, it is preferable that the insulating plate is formed up to a position reaching an exhaust chamber continuously provided at a lower portion of the processing container.

  The plasma processing method of the present invention includes a processing container having an open top for processing an object to be processed using plasma, a mounting table on which the object to be processed is mounted in the processing container, embedded in the mounting table, A first electrode for applying a bias voltage to the processing body; a dielectric plate for blocking the opening of the processing container to define a plasma generation space and transmitting microwaves into the processing container; and A planar antenna provided above the dielectric plate and introducing the microwave generated by the microwave generator into the processing container via the dielectric plate and an upper part of the processing container, forming an annular shape And a lid member that protrudes toward the plasma generation space on the inner peripheral side thereof, and a lid member that supports the outer peripheral portion of the dielectric plate on the upper surface of the corresponding contact support portion, and the processing container or the From the contact support At least a portion of the second electrode protruding toward the plasma generation space in the processing container with a gap between the dielectric plate and paired with the first electrode across the plasma generation space Plasma is generated in the processing container using a plasma processing apparatus including an annular extended protrusion that constitutes a space, and a space formed between an upper surface of the extended protrusion and a lower surface of the dielectric plate. Then, the object to be processed is processed by the plasma. In this case, the processing pressure may be 40 Pa or less.

  The plasma processing apparatus of the present invention protrudes from the processing container or the contact support portion toward the plasma generation space with a gap between the dielectric plate and a pair with the plasma generation space separated from the first electrode. Since the extended protrusion part which comprises at least one part of the 2nd electrode to comprise is provided, the area of a 2nd electrode is fully ensured and the oscillation of plasma potential (Vp) can be suppressed. Further, by increasing the area of the second electrode, the surface of the second electrode is prevented from being sputtered by the action of plasma, and contamination can be prevented. Further, by ensuring the area of the second electrode with a sufficient area, short circuit and abnormal discharge in other parts can be suppressed. Furthermore, since the extended protrusion is provided with a space between the dielectric plate, the effective area of the dielectric plate can be reduced, and sufficient microwave power is introduced to form the inside of the processing vessel. Can stabilize the plasma.

1 is a schematic cross-sectional view of a plasma processing apparatus according to a first embodiment of the present invention. It is sectional drawing which expands and shows the principal part of FIG. It is a perspective view which shows the external appearance of a cover member. It is drawing which shows the structure of a planar antenna. It is a graph which shows the result of having measured the electron density and electron temperature in a processing container about different processing pressures and gaps. It is explanatory drawing which shows the structure of a control part. It is principal part sectional drawing of the plasma processing apparatus which concerns on the 2nd Embodiment of this invention. It is principal part sectional drawing of the plasma processing apparatus which concerns on the 3rd Embodiment of this invention. It is principal part sectional drawing of the plasma processing apparatus which concerns on the 4th Embodiment of this invention. It is principal part sectional drawing of the plasma processing apparatus which concerns on the 5th Embodiment of this invention. It is explanatory drawing which shows the electric potential of a mounting base when a high frequency voltage is applied to the electrode of a mounting base when the electrode area for a bias is inadequate with respect to a counter electrode surface area. It is explanatory drawing which shows the electric potential of a mounting base when a high frequency voltage is applied to the electrode of a mounting base when the electrode area for a bias is enough with respect to a counter electrode surface area. It is a graph which shows the relationship between the amount of aluminum (Al) contamination in plasma oxidation treatment, and Vmax. It is a graph which shows the relationship between counter electrode area ratio (horizontal axis) and Vmax (vertical axis) in plasma oxidation treatment. It is a graph which shows the relationship between counter electrode area ratio (horizontal axis) and Vmax (vertical axis) in the plasma oxidation process on another condition. It is a graph which shows the relationship between the counter electrode area ratio (horizontal axis) and Vmax (vertical axis) in the plasma oxidation process on another condition. It is a graph which shows the relationship between the counter electrode area ratio (horizontal axis) and Vmax (vertical axis) in the plasma oxidation process on another condition. It is a graph which shows the relationship between the counter electrode area ratio (horizontal axis) and Vmax (vertical axis) in the plasma oxidation process on another condition. It is a graph which shows the relationship between the counter electrode area ratio (horizontal axis) and Vmax (vertical axis) in the plasma oxidation process on another condition. It is a graph which shows the quantity of Vmax (vertical axis) at the time of performing a plasma oxidation process by changing process pressure and counter electrode area ratio, and the quantity of aluminum (Al) contamination. It is a graph which shows the measurement result of the oxygen content in the center part of the wafer in a plasma nitriding process. It is a graph which shows the measurement result of the oxygen content in the edge part of the wafer in a plasma nitriding process. It is principal part sectional drawing which shows the modification of the plasma processing apparatus which concerns on the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view schematically showing a schematic configuration of a plasma processing apparatus 100 according to a first embodiment of a plasma processing apparatus of the present invention. FIG. 2A is an enlarged cross-sectional view showing a main part of FIG. FIG. 2B is an external perspective view of a lid member that is a constituent member of the plasma processing apparatus 100. FIG. 3A is a plan view showing a planar antenna of the plasma processing apparatus 100 of FIG.

The plasma processing apparatus 100 uses a planar antenna having a plurality of slot-shaped holes, in particular, RLSA (Radial Line Slot Antenna) to introduce microwaves into the processing container so that the density is low. It is configured as an RLSA microwave plasma processing apparatus that can generate microwave-excited plasma having an electron temperature. In the plasma processing apparatus 100, processing with plasma having a plasma density of 1 × 10 10 to 5 × 10 12 / cm 3 and a low electron temperature of 0.7 to 2 eV is possible. Accordingly, in the manufacturing process of various semiconductor devices, the plasma processing apparatus 100 oxidizes silicon to be processed, for example, to form a silicon oxide film (for example, SiO 2 film), or nitrides to form a silicon nitride film (for example, SiN film). ) Can be suitably used for the purpose of forming.

  The plasma processing apparatus 100 is configured to be hermetically sealed and includes a substantially cylindrical processing container 1 for accommodating a semiconductor wafer (hereinafter simply referred to as “wafer”) W which is an object to be processed. The processing container 1 has a ground potential and is made of a metal material such as aluminum or an alloy thereof, or stainless steel. In addition, the processing container 1 may be divided | segmented into several parts instead of a single container. In addition, a microwave introduction part 26 for introducing a microwave into the plasma generation space S is provided on the upper part of the processing container 1 so as to be openable and closable. That is, the microwave introduction unit 26 is disposed at the upper end of the processing container 1. An exhaust chamber 11 is connected to the lower portion of the processing container 1. A plurality of cooling water flow paths 3 a are formed in the processing container 1 so that the walls of the processing container 1 can be cooled. Accordingly, it is possible to suppress the occurrence of positional displacement and plasma damage of the contact surface portion with the microwave introduction portion 26 due to thermal expansion due to the heat of the plasma, thereby preventing the deterioration of the sealing performance and the generation of particles.

In the processing container 1, a mounting table 5 for horizontally supporting the wafer W is provided in a state of being supported by a cylindrical support portion 4 extending upward from the center of the bottom of the exhaust chamber 11. Examples of the material constituting the mounting table 5 and the support portion 4 include ceramic materials such as quartz, AlN, and Al 2 O 3 , and among these, AlN having good thermal conductivity is preferable. In addition, a resistance heating type heater 5a is embedded in the mounting table 5, and the mounting table 5 is heated by being supplied with power from a heater power source 6 which is, for example, a 200V AC power source. The wafer W is heated. The power supply line 6a that connects the heater 5a and the heater power supply 6 is provided with a filter box 45 that filters RF (high frequency). The temperature of the mounting table 5 is measured by a thermocouple (not shown) inserted in the mounting table 5, and the heater power supply 6 is controlled based on a signal from the thermocouple. For example, the temperature control is stable in a range from room temperature to 800 ° C. Is possible.

  A bias electrode 7 as a first electrode is buried above the heater 5 a on the surface side inside the mounting table 5. The electrode 7 is embedded in a region substantially corresponding to the wafer W placed on the mounting table 5. As a material of the electrode 7, for example, a conductive material such as molybdenum or tungsten can be used. The electrode 7 is formed, for example, in a mesh shape, a lattice shape, a spiral shape, or the like. A cover 8a is provided so as to cover the surface of the mounting table 5 and the entire side wall. The cover 8a prevents the plasma on the mounting table 5 from being sputtered and causing metal contamination. In order to guide the wafer W, a recess (groove) that is larger than the wafer size and substantially the same depth as the thickness of the wafer W is provided on the surface of the cover 8a. The wafer W is placed in this recess. A quartz baffle plate 8b is annularly provided around the mounting table 5 in order to uniformly exhaust the inside of the processing vessel 1. The baffle plate 8b has a plurality of holes 8c and is supported by a column (not shown). Furthermore, the mounting table 5 is provided with a plurality of wafer support pins (not shown) for supporting the wafer W and raising and lowering it so as to protrude and retract with respect to the surface of the mounting table 5.

  A circular opening 10 is formed at a substantially central portion of the bottom wall 1a of the processing container 1, and the bottom wall 1a communicates with the opening 10 and protrudes downward to make the inside of the processing container 1 uniform. An exhaust chamber 11 for exhausting air is continuously provided. An exhaust port 11b is formed on the side surface of the exhaust chamber 11, and an exhaust pipe 23 is connected thereto. An exhaust device 24 including a vacuum pump is connected to the exhaust pipe 23. Then, by operating the exhaust device 24, the gas in the processing container 1 is uniformly discharged into the space 11 a of the exhaust chamber 11 and is exhausted through the exhaust pipe 23. Thereby, the inside of the processing container 1 can be depressurized at a high speed to a predetermined degree of vacuum, for example, 0.133 Pa. The exhaust pipe 23 may be connected to the bottom surface of the exhaust chamber 11. The exhaust chamber 11 may be formed inside the processing container 1.

  Note that a loading / unloading port for loading / unloading the wafer W and a gate valve for opening / closing the loading / unloading port are provided on the side wall 1b of the processing chamber 1 (none of which is shown).

  The upper part of the processing container 1 is an opening, and the microwave introduction part 26 can be airtightly arranged so as to close the opening. The microwave introduction unit 26 can be opened and closed by an opening / closing mechanism (not shown). The microwave introduction part 26 has a lid member 27, a microwave transmission plate 28, a planar antenna 31, and a slow wave material 33 in this order from the mounting table 5 side, and further, the slow wave material 33. For example, a conductive cover 34 made of a material such as SUS, aluminum, or an alloy thereof is covered. The outer peripheral portion of the cover 34 is fixed to the lid member 27 by an annular pressing ring 35 via a fixing member 36.

  The lid member 27 has a ground potential and is formed of the same material as that of the processing container 1. In the present embodiment, the annular lid member 27 has an opening. The inner peripheral portion of the lid member 27 is exposed to the plasma generation space S in the processing container 1 and constitutes a counter electrode as a second electrode facing the electrode 7 of the mounting table 5 as a lower electrode. An inner peripheral surface of the annular lid member 27 forms a protruding portion 60 that protrudes toward the plasma generation space S from the inner wall surface of the processing container 1. As shown in FIGS. 2A and 2B, the projecting portion 60 has an abutment support portion 60A that abuts and supports the microwave transmitting plate 28 on its upper surface, and plasma in the processing chamber 1 further than the corresponding contact support portion 60A. It has the extended protrusion part 60B which protrudes greatly toward the production | generation space S. As shown in FIG. The contact support 60A and the extended protrusion 60B form a step, and when the microwave transmission plate 28 is disposed on the contact support 60A, an annular space S1 is formed between the microwave transmission plate 28 and the expansion protrusion 60B. Is formed. In the present embodiment, this extended protrusion 60B is a part that functions centrally as a counter electrode. The space S1 constitutes a part of the plasma generation space S.

  Further, the gas introduction ports 15a are equally provided at a plurality of locations (for example, 32 locations) on the inner peripheral surface of the contact support portion 60A of the lid member 27. That is, the gas introduction ports 15a are opened in an annular manner on the wall of the contact support portion 60A that forms a step between the contact support portion 60A and the extended protrusion 60B. Each gas inlet 15a is opened facing the space S1 so that the processing gas can be introduced into the space S1. A gas introduction path 15b extending obliquely from each of the gas introduction ports 15a to the inside of the lid member 27 is provided. The gas introduction path 15b may be formed horizontally. Each gas introduction path 15 b communicates with the annular passage 13 formed in the horizontal direction between the lid member 27 and the upper portion of the processing container 1. As a result, the processing gas can be uniformly supplied to the plasma generation space S and the space S1 in the processing container 1.

  Sealing members 9a and 9b such as O-rings are disposed on the outer side and the inner side along the annular passage 13 at the abutting portion between the processing container 1 and the lid member 27, whereby the abutting portion is airtight. Is preserved. That is, in the state where the microwave introduction part 26 is closed, the upper end surface of the side wall 1b of the processing container 1 and the lid member 27 having an opening / closing function are sealed by the seal members 9a and 9b. The seal members 9a and 9b are made of, for example, a fluorine rubber material such as Kalrez (trade name; manufactured by DuPont). In addition, a plurality of refrigerant channels 27 a are formed on the outer peripheral surface of the lid member 27. The outer periphery of the lid member 27 and the microwave transmission plate 28 can be cooled by flowing the refrigerant through the refrigerant flow path 27a. As a result, the occurrence of displacement of the contact surface portion due to thermal expansion caused by the heat of the plasma is prevented, and the deterioration of the sealing performance and the generation of particles are prevented.

The microwave transmission plate 28 as a dielectric plate is made of a dielectric material such as quartz, Al 2 O 3 , AlN, sapphire, or SiN. The microwave transmission plate 28 functions as a microwave introduction window that transmits the microwave from the planar antenna 31 and introduces it into the plasma generation space S in the processing container 1. The lower surface (the mounting table 5 side) of the microwave transmission plate 28 is not limited to a flat shape, and, for example, a recess or a groove may be formed in order to make the microwave uniform and stabilize the plasma.

  The outer peripheral portion of the microwave transmitting plate 28 is supported in an airtight state on the contact support portion 60 </ b> A of the protruding portion 60 of the lid member 27 via the seal member 29. Therefore, the plasma generation space S is defined by the processing container 1 and the microwave transmission plate 28 in a state where the microwave introduction unit 26 is closed, and the plasma generation space S is kept airtight.

  The planar antenna 31 has a disk shape and is locked by the outer peripheral portion of the cover 34 above the microwave transmission plate 28. The planar antenna 31 is made of, for example, a metal plate such as a copper plate, an aluminum plate, a nickel plate, or a brass plate whose surface is plated with gold or silver, and has a number of slot holes 32 for radiating electromagnetic waves such as microwaves. ing. The slot holes 32 are formed through the planar antenna 31, and two holes are arranged in a predetermined pattern in pairs.

  The slot holes 32 have, for example, a long groove shape as shown in FIG. 3A. Typically, adjacent slot holes 32 are arranged in a “T” shape, and the plurality of slot holes 32 are arranged concentrically. Yes. The length and arrangement interval of the slot holes 32 are determined according to the wavelength (λg) of the microwave in the waveguide 37. For example, the interval of the slot holes 32 is arranged to be λg / 4 to λg. In FIG. 3A, the interval between adjacent slot holes 32 formed concentrically is indicated by Δr. The slot hole 32 may have other shapes such as a circular shape and an arc shape. Furthermore, the arrangement form of the slot holes 32 is not particularly limited, and the slot holes 32 may be arranged concentrically, for example, spirally or radially.

  The slow wave material 33 has a dielectric constant larger than that of the vacuum, and is provided on the upper surface of the planar antenna 31. The slow wave material 33 is made of, for example, fluorine resin such as quartz, ceramics, polytetrafluoroethylene, or polyimide resin. And since the wavelength of a microwave becomes long in a vacuum, it has the function to shorten the wavelength of a microwave and to adjust plasma. The planar antenna 31 and the microwave transmission plate 28 and the slow wave member 33 and the planar antenna 31 may be in close contact with each other or may be separated from each other, but are preferably in close contact with each other.

  The cover 34 is formed with a refrigerant flow path 34 a, and the cover 34, the slow wave material 33, the planar antenna 31, the microwave transmission plate 28, and the lid member 27 are cooled by allowing the refrigerant to flow therethrough. It has become. Thereby, it is possible to prevent the deformation and breakage of these members and to generate stable plasma. The planar antenna 31 and the cover 34 are grounded.

  An opening 34b is formed at the upper center of the cover 34, and a waveguide 37 is connected to the opening 34b. A microwave generator 39 is connected to the end of the waveguide 37 via a matching circuit 38. Thereby, for example, a microwave having a frequency of 2.45 GHz generated by the microwave generator 39 is propagated to the planar antenna 31 through the waveguide 37. As the microwave frequency, 8.35 GHz, 1.98 GHz, or the like can be used.

  The waveguide 37 is connected to a coaxial waveguide 37a having a cylindrical section extending upward from the opening 34b of the cover 34, and an upper end portion of the coaxial waveguide 37a via a mode converter 40. And a rectangular waveguide 37b extending in the horizontal direction. The mode converter 40 between the rectangular waveguide 37b and the coaxial waveguide 37a has a function of converting the microwave propagating in the TE mode in the rectangular waveguide 37b into the TEM mode. An inner conductor 41 extends from the mode converter 40 to the planar antenna 31 at the center of the coaxial waveguide 37a, and the inner conductor 41 is connected and fixed to the center of the planar antenna 31 at its lower end. . A flat waveguide is formed by the planar antenna 31 and the cover 34. As a result, the microwave is introduced into the central portion of the planar antenna 31 via the inner conductor 41 of the coaxial waveguide 37a, and is efficiently propagated radially and uniformly therefrom.

  Next, a gas supply structure in the plasma processing apparatus 100 will be described. As shown in FIG. 2A in an enlarged manner, a plurality of gas supplies are provided at arbitrary positions (for example, four equal positions) on the side wall 1b of the processing container 1 through the inside of the side wall 1b and the bottom wall 1a in the vertical direction. A path 12 is formed. The gas supply path 12 is connected to an annular passage 13 formed in a contact surface portion between the upper end portion of the side wall 1 b of the processing container 1 and the lower end portion of the lid member 27. The annular passage 13 is connected to a gas supply device 16 through a gas supply path 12 and a gas supply pipe 12a. In addition, it is good also as a structure which connects the gas supply apparatus 16 to the annular channel | path 13 from the side surface of the processing container 1 by forming a gas supply path in a horizontal direction.

  The annular passage 13 is a gas flow path formed by the step portion 18 and the step portion 19 at a contact portion between the upper end surface of the processing container 1 and the lower end surface of the lid member 27. The step portion 18 is provided on the lower surface of the lid member 27. The step portion 19 is provided on the upper end surface of the side wall 1 b of the processing container 1. The annular passage 13 is formed in an annular shape in a substantially horizontal direction so as to surround the plasma generation space S in the processing container 1. The annular passage 13 may be formed by forming a groove (concave portion) on the upper end surface of the side wall 1 b of the processing container 1 or the lower surface of the lid member 27. The annular passage 13 has a function as a gas distribution means for supplying the gas to the gas introduction passages 15b evenly, and the processing gas is supplied to the specific gas introduction port 15a so as to be distributed in the processing vessel 1. It functions to prevent uneven supply. As described above, in the present embodiment, the processing gas from the gas supply device 16 is uniformly supplied to the processing container 1 from, for example, the 32 gas inlets 15a through the gas supply passages 12, the annular passages 13, and the gas introduction passages 15b. Since the plasma can be introduced into the plasma generation space S and the space S1, the uniformity of the plasma in the processing vessel 1 can be improved.

  Next, bias voltage applying means for applying a bias voltage to the wafer W placed on the mounting table 5 will be described. A high frequency power supply 44 for bias application is connected to the electrode 7 embedded in the mounting table 5 via a feeder line 42 and a matching box (MB) 43 that pass through the support portion 4. In this configuration, a high frequency bias can be applied. As described above, the filter box 45 is provided in the power supply line 6a that supplies power from the heater power source 6 to the heater 5a. The matching box 43 and the filter box 45 are connected through a shield box 46 to be unitized, and are attached to the bottom of the exhaust chamber 11. The shield box 46 is formed of a conductive material such as aluminum or SUS, for example. In the shield box 46, a conductive plate 47 made of a material such as copper connected to the power supply line 42 is provided and connected to a matcher (not shown) in the matching box 43. By using the conductive plate 47, it is possible to increase the contact area with the feeder line 42, reduce the contact resistance, and reduce the current loss at the connection portion. As described above, in the plasma processing apparatus 100 of the present embodiment, the matching box 43 and the filter box 45 are connected and unitized via the shield box 46, and directly connected to the lower portion of the exhaust chamber 11 of the processing container 1. Therefore, the loss of the high frequency power supplied from the high frequency power supply 44 to the electrode 7 can be reduced, the power consumption efficiency can be improved, and the power can be supplied stably. As a result, a high-frequency bias can be stably applied to the wafer W placed on the mounting table 5, so that the plasma generated in the processing chamber 1 is stabilized and uniform plasma processing is possible.

  As described above, on the inner peripheral side of the lid member 27, as a part of the lid member 27, the protruding portion 60 having the contact support portion 60A and the extended protruding portion 60B is formed. Thus, by forming the lid member 27 and the protruding portion 60 integrally, thermal conductivity and electrical conductivity can be ensured. The extended protrusion 60B of the protrusion 60 has an upper surface 60B1, a tip surface 60B2, and a lower surface 60B3. These protrusions 60 are formed facing the plasma generation space S, and are opposed electrodes (second electrodes) facing the electrode 7 of the mounting table 5 serving as the first electrode with the plasma generation space S therebetween. ) Is the main part that functions as. Specifically, the exposed surface of the protrusion 60 from a portion A indicated by a circle in FIG. 2A, which is the end of the contact portion between the contact support portion 60A of the lid member 27 and the microwave transmitting plate 28 in FIG. 2A. (In other words, the portion indicated by a circle in the drawing is the end of the exposed lower surface of the contact support portion 60A that bypasses the surface of the contact support portion 60A and the upper surface 60B1, the front end surface 60B2, and the lower surface 60B3 of the extended protrusion 60B). The surface that reaches B (the contact end with the upper liner 49a) is a portion that functions as a counter electrode. In the present embodiment, the inner peripheral surface of the annular lid member 27 extending from the part A to the part B is exposed to the plasma generation space S to form an annular counter electrode. As described above, by providing the annular member that mainly serves as the counter electrode so as to protrude into the plasma generation space, the counter electrode can be disposed at a position immediately above the mounting table 5 because the microwave transmitting plate 28 is provided. Even in the difficult RLSA-type plasma processing apparatus 100, the surface area of the counter electrode can be sufficiently large.

In plasma processing apparatus 100 of the present embodiment, a portion that functions as a counter electrode with respect to the lower electrode is defined as a conductive member that is exposed to plasma generation space S and is at a ground potential. it can. As will be described later, since the protective film 48 can be provided on the surface of the counter electrode, “exposed to the plasma generation space S” includes a state covered with the protective film 48. Further, as a more specific definition for functioning as a counter electrode, for example, the counter electrode has an exposed surface facing the plasma generation space S above the wafer mounting surface of the mounting table 5, and in the processing chamber 1. It is also possible to use a conductive member that is exposed to plasma having an electron density of 1 × 10 11 / cm 3 or more when plasma is generated. However, the value of the electron density is merely an example, and is not limited to this number. For example, FIG. 3B shows a case where the microwave transmission plate 28 in the processing chamber 1 is changed when the processing pressure and the gap G (distance from the surface of the wafer W to the microwave transmission plate 28) are changed in the plasma processing apparatus 100. The result of having measured the electron density and the electron temperature in the site | part just under a center part is shown. Thus, since the electron density and the electron temperature of the plasma generated in the processing container 1 also change depending on the processing pressure and the gap G, it is preferable to adjust the counter electrode surface area according to the processing pressure and the gap G. The gap G is preferably in the range of 50 mm to 150 mm, for example, and more preferably in the range of 70 mm to 120 mm.

  The area of the portion functioning as the counter electrode exposed to the plasma generation space S (may be referred to as “counter electrode surface area” in this specification) is the area of the embedded region of the electrode 7 in the mounting table 5 (this specification). The area ratio to the “bias electrode area” is preferably 1 or more, more preferably 1 or more and 5 or less, and more preferably 1 or more and 4 or less. Is more preferable, and it is desirable that it is in the range of 2 or more and 4 or less. When the ratio of the counter electrode surface area to the bias electrode area (counter electrode surface area / bias electrode area) is less than 1, the oscillation of the plasma potential increases and stable plasma cannot be generated in the processing chamber 1. At the same time, the sputtering effect by the plasma in the vicinity of the counter electrode is strengthened, and the surface of the counter electrode is shaved, which may cause aluminum contamination. Further, the ratio of the counter electrode surface area to the bias electrode area (counter electrode surface area / bias electrode area) is preferably as large as possible. However, the upper limit may be set to 5 due to device size and structural restrictions, and 4 or less. It is preferable that In addition, the area of the embedding region of the electrode 7 in the mounting table 5 refers to, for example, the electrode 7 having a shape such as a mesh shape, a lattice shape, a spiral shape or the like having an opening or a gap, and a flat surface including the opening or the gap portion. This means the area of the planar region when considered.

The tip of the protrusion 60 functioning as a counter electrode (tip surface 60B2 of the extended protrusion 60B) does not reach the upper side of the wafer W (the position P WE of the peripheral edge of the wafer W) placed on the mounting table 5. The length is preferred. The tip of the projecting portion 60 is, when the position P WE of the peripheral edge of the wafer W reaches the inner, the magnitude of the high-density, uniform plasma generated in the processing chamber 1 is smaller than the wafer size, the peripheral portion of the wafer W The plasma density may be reduced, and the uniformity of the processing content at the outer periphery of the wafer W may be adversely affected. On the other hand, the protruding portion 60 that functions as a counter electrode has a base end portion at the contact end with the side wall 1b on the opposite side (the side wall 1b side of the processing container 1) of the tip end portion (tip surface 60B2). In the embodiment, it suffices that the portion B in the middle is exposed to the plasma generation space S. That is, in the present embodiment, the exposed end of the lower surface 60B3 of the protruding portion 60 that functions as a counter electrode is a contact point with the upper liner 49a indicated by the portion B in FIG.

  Further, the upper surface 60B1 of the extended protrusion 60B that faces the space S1 is disposed away from the lower surface of the microwave transmission plate 28. That is, the extended protrusion 60 </ b> B protrudes toward the plasma generation space S with a gap L <b> 1 from the microwave transmission plate 28. In this way, by providing the gap L1 between the microwave transmission plate 28 and the extended protrusion 60B, the surface area of the microwave transmission plate 28 as a counter electrode can be increased without reducing the effective area for introducing the microwave. It can be secured sufficiently wide. Further, the space S1 becomes a part of the plasma generation space S, and plasma is generated also in the space S1, so that the plasma in the processing container 1 can be stably maintained. On the other hand, when the microwave transmitting plate 28 and the extended protrusion 60B are disposed in close contact with each other without providing the interval L1 as in the conventional plasma processing apparatus, the surface area of the counter electrode in the processing container 1 should be increased. Then, it is necessary to increase the amount of protrusion of the microwave transmission plate 28 toward the center. Then, when the plasma is generated, the effective area of the microwave transmission plate 28 is reduced by the contact area with the upper surface 60B1 of the extended protrusion 60B, so that the amount of microwave power supplied into the processing container 1 is reduced. As a result, plasma is not generated or even if it is generated, it becomes unstable. In order to solve this, it is necessary to enlarge the processing container 1, but the installation area increases and the manufacturing cost of the apparatus also increases. When the microwave transmitting plate 28 and the extended protrusion 60B are disposed in close contact with each other, the surface of the counter electrode near the contact point between the microwave transmitting plate 28 and the counter electrode (that is, the tip of the extended protruding portion 60B) has a high density. Sputtering with plasma makes it easier to generate metal contamination.

  This distance L1 is preferably larger than the thickness of the sheath between the plasma generated immediately below the microwave transmission plate 28 and the microwave transmission plate 28, and is sufficiently larger than the mean free path of electrons. Preferably there is. For example, in the plasma processing apparatus 100 of FIG. 1, when the processing pressure is 6.7 Pa, the sheath thickness is about 0.25 mm when the high frequency bias voltage is applied, and the mean free path of electrons is about 8 mm. Therefore, the distance L1 is preferably in the range of 10 mm to 30 mm, for example, and more preferably in the range of 20 mm to 25 mm. By setting the interval L1 within the above range, stable plasma can be maintained in the processing container 1. If the interval L1 is less than 10 mm, the plasma may not be stabilized because abnormal discharge occurs in the space S1, and particularly when the interval L1 is less than the sheath thickness, it is difficult to generate plasma in the processing vessel 1. There is a case. On the other hand, if the distance L1 exceeds 30 mm, the extended protrusion 60B becomes too close to the electrode 7 of the mounting table 5, and thus it becomes difficult to function as a counter electrode. Further, the extended protrusion 60B is thermally damaged by the heat of the mounting table 5. There is a possibility.

  Similarly, the upper limit of the thickness L2 of the extended protrusion 60B (that is, the distance between the upper surface 60B1 and the lower surface 60B3) L2 is, for example, 20 mm in order to avoid the extended protrusion 60B from being too close to the electrode 7 of the mounting table 5. It is preferable to do. However, if the thickness L2 of the extended protrusion 60B is too small, the effect as the counter electrode is reduced. Therefore, the lower limit of the thickness L2 is preferably set to 5 mm, for example. Therefore, the thickness L2 of the extended protrusion 60B is preferably in the range of 5 mm to 20 mm, and more preferably in the range of 7 mm to 17 mm.

  Furthermore, the distance L3 (here, the difference in height position between both members) from the lower surface 60B3 of the extended protrusion 60B to the upper surface of the mounting table 5 is expanded while functioning the extended protrusion 60B as a counter electrode. In order to avoid the protrusion 60B from being too close to the electrode 7 of the mounting table 5, for example, it is preferably in the range of 15 mm to 60 mm, and more preferably in the range of 20 mm to 25 mm.

  Further, in the plasma processing apparatus 100 of the present embodiment, the gas introduction port 15a is provided at a position above the extended protrusion 60B, and the processing gas is supplied to the space S1 between the extended protrusion 60B and the microwave transmission plate 28. It was set as the structure to do. With this configuration, it is possible to promote the replacement and discharge of the gas in the space S1 directly below the microwave transmission plate 28 and to easily activate the processing gas. As a result, plasma can be efficiently generated in the entire space S1 immediately below the microwave transmission plate 28. The space S1 is a part of the plasma generation space S. As another effect, as shown in an example described later, when a plasma nitridation process is performed in the plasma processing apparatus 100 by supplying a processing gas to the space S1 directly below the microwave transmission plate 28, a quartz-made material is used. Since discharge of oxygen released from the microwave transmission plate 28 to the outside of the processing container 1 can be promoted, a decrease in the nitrogen concentration in the nitride film to be formed can be suppressed. Note that oxygen is released from the microwave transmission plate 28 when oxygen originally present in the quartz microwave transmission plate 28 is released, and when a wafer having an oxide film in the past in the plasma processing apparatus 100 is used. It is conceivable that oxygen released from the wafer W is once adsorbed by the microwave transmission plate 28 when the plasma treatment of W is performed, and the oxygen is released during the plasma nitriding treatment.

In plasma processing apparatus 100 of the present embodiment, protective film 48 is provided on the exposed surface of protrusion 60 of lid member 27 that constitutes the counter electrode. That is, since the lid member 27 is made of a metal such as aluminum or an alloy thereof, for example, the lid member 27 is enlarged in FIG. 2A in order to prevent exposure to plasma and sputtering to generate metal contamination and particles. As described above, the protective film 48 is coated. The protective film 48 is formed on the surface of the contact support portion 60A and the upper surface 60B1, the tip surface 60B2, and the lower surface 60B3 of the extended protrusion 60B. The material of the protective film 48 is preferably silicon in consideration of contamination and particle generation due to the protective film 48 being cut. The silicon may have a crystal structure such as single crystal silicon or polycrystalline silicon, or may have an amorphous structure. Even if the protective film 48 is formed on the protruding portion 60, the function as the counter electrode is maintained, and stable plasma is generated and uniform plasma processing is possible. The protective film 48 efficiently forms a high-frequency current path that flows from the mounting table 5 across the plasma generation space S to the lid member 27 via the projecting portion 60 that is a counter electrode, thereby causing a short circuit or abnormal discharge in other parts. At the same time, the surface of the counter electrode is protected from the oxidizing action and sputtering action by the plasma, and the occurrence of contamination by a metal such as aluminum which is a constituent material of the counter electrode is suppressed. Further, when a silicon film is formed as the protective film 48, even if the silicon film is oxidized by plasma oxidizing action to become a silicon dioxide film (SiO 2 film), it is very thin and the product of dielectric constant and resistivity. Is a small material, the current path flowing from the mounting table 5 to the lid member 27 that is the counter electrode across the plasma generation space S is hardly obstructed, and a stable and appropriate high-frequency current path can be maintained.

The silicon film as the protective film 48 is preferably a dense and low resistivity film with a small porosity in the film. When the porosity in the film increases, the volume resistivity also increases. For example, the porosity is in the range of 1 to 10%, and the volume resistivity is in the range of 5 × 10 4 to 5 × 10 5 Ω · cm 2 . It is preferable that Such a silicon film is preferably formed by plasma spraying, for example. The thickness of the protective film 48 is preferably in the range of 10 to 800 μm, more preferably in the range of 50 to 500 μm, and preferably in the range of 50 to 150 μm. If the thickness of the protective film 48 is less than 10 μm, a sufficient protective action cannot be obtained, and if it exceeds 800 μm, cracks, peeling and the like are likely to occur due to stress.

  The protective film 48 can be formed by a thin film forming technique such as PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) in addition to the plasma spraying method, for example. Among them, a thermal spraying method that can form a protective film 48 that is relatively inexpensive, easy to process, and easily controllable so that the porosity and volume resistivity are within good ranges is preferable. Thermal spraying methods include flame spraying, arc spraying, laser spraying, plasma spraying, and the like, but plasma spraying capable of forming a high-purity film with good controllability is preferable. Examples of the plasma spraying method include an atmospheric pressure plasma spraying method and a vacuum plasma spraying method, either of which can be used.

As the protective film 48, for example, TiN, Y 2 O 3 , Al 2 O 3 , SiO 2 or the like can be used instead of silicon.

  In the plasma processing apparatus 100 according to the present embodiment, a cylindrical liner made of quartz is provided on the inner periphery of the processing container 1. The liner mainly serves as an upper liner 49a as a first insulating plate that covers the upper inner surface of the processing container 1, and as a second insulating plate that covers the upper liner 49a and mainly covers the lower inner surface of the processing container 1. The lower liner 49b is included. The upper liner 49a and the lower liner 49b prevent the wall of the processing container 1 from contacting the plasma, prevent metal contamination due to the constituent material of the processing container 1, and from the mounting table 5 toward the side wall 1b of the processing container 1. It works so as not to cause short circuit and abnormal discharge of high frequency current. The lower liner 49b provided at a position close to the mounting table 5 with a small distance is formed to be thicker than the upper liner 49a. The thicknesses of the upper liner 49a and the lower liner 49b may be set so as not to cause a short circuit of high-frequency current or abnormal discharge, and to consider impedance. For example, it is preferable to set the lower liner 49b to be thicker than the upper liner 49a within the range of 2 mm to 30 mm.

Further, the lower liner 49b is provided so as to cover at least a part of the inner surface of the processing container 1 and the exhaust chamber 11 at a height position lower than the height of the mounting table 5 in which the electrode 7 is embedded, and preferably almost the whole. This is because, in the lower part of the mounting table 5, in order to prevent the distance between the mounting table 5 and the processing container 1 from becoming shortest, abnormal discharge at this part is prevented. The material of the upper liner 49a and the lower liner 49b is preferably quartz, but a dielectric such as ceramics such as Al 2 O 3 , AlN, Y 2 O 3 can also be applied. The upper liner 49a and the lower liner 49b may be formed by coating the above materials. Further, for example, the surface of the upper liner 49a and the lower liner 49b made of aluminum may be used by coating, for example, a SiO 2 film by a plasma spraying method.

  Each component of the plasma processing apparatus 100 is connected to and controlled by a control unit 50 having a computer. For example, as illustrated in FIG. 4, the control unit 50 includes a process controller 51 including a CPU, a user interface 52 connected to the process controller 51, and a storage unit 53. In the plasma processing apparatus 100, the process controller 51 is a component (for example, the heater power supply 6, the gas supply apparatus 16) related to process conditions such as temperature, pressure, gas flow rate, microwave output, and high frequency power for bias application. , An exhaust device 24, a microwave generator 39, a high-frequency power source 44, etc.).

  The user interface 52 includes a keyboard on which a process manager manages command input to manage the plasma processing apparatus 100, a display that visualizes and displays the operating status of the plasma processing apparatus 100, and the like. The storage unit 53 stores a control program (software) for realizing various processes executed by the plasma processing apparatus 100 under the control of the process controller 51, a recipe in which processing condition data, and the like are recorded. ing.

  If necessary, an arbitrary recipe is called from the storage unit 53 by an instruction from the user interface 52 and is executed by the process controller 51, so that the processing container of the plasma processing apparatus 100 is controlled under the control of the process controller 51. The desired processing is performed within 1. The recipe such as the control program and processing condition data can be stored in a computer-readable storage medium such as a CD-ROM, hard disk, flexible disk, flash memory, DVD, or Blu-ray disk. Furthermore, it is possible to transmit the recipe from another apparatus, for example, via a dedicated line.

  In the plasma processing apparatus 100 of the present invention configured as described above, damage-free plasma oxidation processing or plasma nitriding processing to a base film, a substrate (wafer W) or the like is performed at a low temperature of, for example, room temperature (about 25 ° C.) to 600 ° C. Etc. can be performed. Further, since the plasma processing apparatus 100 is excellent in plasma uniformity, process uniformity can be realized even for a large-diameter wafer W (object to be processed).

Next, the operation of the plasma processing apparatus 100 will be described. First, the wafer W is loaded into the processing container 1 and placed on the mounting table 5. Then, the processing gas is introduced from the gas supply device 16 into the processing container 1 through the gas supply path 12, the annular path 13, and the gas introduction port 15a. As a processing gas, in addition to a rare gas such as Ar, Kr, and He, for example, in the case of plasma oxidation treatment, for example, an oxidizing gas such as O 2 , N 2 O, NO, NO 2 , CO 2 , or plasma nitriding treatment Supplies a nitrogen-containing gas such as N 2 or NH 3 at a predetermined flow rate. In the case of plasma oxidation treatment, H 2 may be added as necessary.

  Next, the microwave from the microwave generator 39 is guided to the waveguide 37 through the matching circuit 38, and is sequentially passed through the rectangular waveguide 37b, the mode converter 40, and the coaxial waveguide 37a. It is supplied to the planar antenna 31 via 41 and radiated into the processing container 1 from the slot hole 32 of the planar antenna 31 via the microwave transmitting plate 28. During this time, the microwave propagates in the TE mode in the rectangular waveguide 37b, and the TE mode microwave is converted into the TEM mode by the mode converter 40, and the coaxial waveguide 37a is directed to the planar antenna 31. Will be propagated. An electromagnetic field is formed in the processing container 1 by the microwave radiated from the planar antenna 31 to the processing container 1 through the microwave transmission plate 28, and the processing gas is turned into plasma.

This plasma has a high density of about 1 × 10 10 to 5 × 10 12 / cm 3 due to microwaves radiated from a large number of slot holes 32 of the planar antenna 31, and in the vicinity of the wafer W, about 1. It becomes a low electron temperature plasma of 5 eV or less. Therefore, by causing this plasma to act on the wafer W, processing that suppresses plasma damage is possible.

  In the present embodiment, high-frequency power is supplied from the high-frequency power supply 44 to the electrode 7 of the mounting table 5 at a predetermined frequency during the plasma processing. The frequency of the high frequency power supplied from the high frequency power supply 44 is preferably in the range of 100 kHz to 60 MHz, for example, and more preferably in the range of 400 kHz to 13.5 MHz. By setting the frequency of the high frequency power within the above range, a negative bias is efficiently applied to the mounting table 5.

RF power is preferably supplied at a range as the power density for example of 0.2 W / cm 2 or more 2.3 W / cm 2 or less per area of the wafer W, 0.35 W / cm 2 or more 1.2 W / cm It is more preferable to supply within the range of 2 or less. By setting the high frequency power density within the above range, a negative bias is efficiently applied to the mounting table 5.

  The high frequency power is preferably in the range of 200 W to 2000 W, and more preferably in the range of 300 W to 1200 W. By setting the high frequency power within the above range, a negative bias is efficiently applied to the mounting table 5.

  The high frequency power supplied to the electrode 7 of the mounting table 5 has an action of drawing ion species in the plasma into the wafer W while maintaining a low electron temperature of the plasma. Therefore, by supplying high-frequency power to the electrode 7 and applying a bias to the wafer W, the rate of plasma oxidation treatment or plasma nitridation treatment can be increased, and the uniformity of the treatment within the wafer surface can be improved.

  In this case, the electrodes of the mounting table 5 are provided with a low power loss from the high frequency power supply 44 via the unitized high frequency power introduction part (the conductive plate 47 in the matching box 43 and the shield box 46) and the power supply line 42. 7 is efficiently supplied with high frequency power. The high-frequency power supplied to the electrode 7 is transmitted from the mounting table 5 through the plasma generation space S to the lid member 27 having the projecting portion 60 that functions as a counter electrode, and the side wall 1b of the processing container 1; Further, a high-frequency current path (RF return circuit) is formed which is transmitted to the ground of the high-frequency power supply 44 through the wall of the exhaust chamber 11. In the present embodiment, by providing the extended protrusion 60B, it is possible to generate a stable plasma in the processing vessel 1 by suppressing the vibration of the plasma potential (Vp), and the plasma is sputtered. It is possible to prevent the surface of the electrode from being scraped and causing metal contamination.

In addition, since the conductive protective film 48 (silicon film or SiO 2 film formed by oxidizing silicon) is provided on the exposed surface of the projecting portion 60 that is the counter electrode facing the plasma generation space S, the counter electrode And the formation of a high-frequency current path through which a high-frequency current appropriately flows from the mounting table 5 to the lid member 27 that is the counter electrode across the plasma generation space S is not hindered. In addition, since the upper liner 49a and the lower liner 49b having a thickness larger than this are provided on the inner surface of the processing vessel 1 adjacent to the protective film 48, short-circuiting and abnormal discharge to these portions are reliably suppressed. can do. That is, the protective film 48 can suppress abnormal discharge and prevent metal contamination.

  As described above, in the plasma processing apparatus 100 according to the present embodiment, the counter electrode surface area is secured sufficiently wide by the extended protrusion 60B of the protrusion 60, which is the counter electrode, and an appropriate high-frequency current path is formed. As a result, the power consumption efficiency of the high frequency power for bias supplied to the electrode 7 of the mounting table 5 on which the wafer W is mounted can be improved. Further, a space S1 is formed between the extended protrusion 60B and the microwave transmission plate 28, and the counter electrode is disposed so as to protrude into the plasma generation space S, thereby generating stable plasma in the plasma generation space S and the space S1. I can do it. In addition, abnormal discharge can be prevented and the process can be made more efficient and stable. Further, since the extended protrusion 60B is provided at a distance L1 from the microwave transmission plate 28, it is possible to introduce sufficient microwave power without reducing the effective area of the microwave transmission plate 28, Plasma formed in the processing container 1 can be stabilized.

[Second Embodiment]
Next, a plasma processing apparatus according to a second embodiment of the present invention will be described with reference to FIG. The plasma processing apparatus 101 according to the second embodiment is the same as the plasma processing apparatus 100 according to the first embodiment except for the features thereof, and therefore the overall configuration is described (FIGS. 1 and 3A). 4) is omitted, and in FIG. 5, the same components as those in FIG.

  In the plasma processing apparatus 101 of the present embodiment, a protrusion 61 is formed on the inner peripheral side of the lid member 27 as a part of the lid member 27. Thus, by forming the lid member 27 and the protruding portion 61 integrally, heat conductivity and conductivity can be ensured. The protrusion 61 has an abutment support 61A and an extended protrusion 61B. The extended protrusion 61B of the protrusion 61 has an upper surface 61B1, a tip surface 61B2, and a lower surface 61B3. The protrusion 61 is formed facing the plasma generation space S, and is a counter electrode (second electrode) that forms a pair with the electrode 7 of the mounting table 5 serving as the first electrode across the plasma generation space S. Is the main part that functions as. Specifically, the exposed surface of the projecting portion 61 from a portion A indicated by a circle in the drawing, which is the end of the contact portion between the contact support portion 61A of the lid member 27 and the microwave transmitting plate 28 in FIG. (In other words, the portion indicated by a circle in the drawing is the end of the exposed lower surface of the contact support portion 61A that bypasses the surface of the contact support portion 61A and the upper surface 61B1, the front end surface 61B2, and the lower surface 61B3 of the extended protrusion 61B). The inner peripheral surface that reaches B (the contact end with the upper liner 49a) is a portion that functions as a counter electrode. In the present embodiment, the surface from the part A to the part B is exposed to the plasma generation space S to form an annular counter electrode. As described above, by providing the annular member that mainly serves as the counter electrode so as to protrude into the plasma generation space, the counter electrode can be disposed at a position immediately above the mounting table 5 because the microwave transmitting plate 28 is provided. Even in the difficult RLSA type microwave plasma processing apparatus 101, a sufficiently large surface area of the counter electrode can be secured.

  In the plasma processing apparatus 101 of the present embodiment, the surface of the extended protrusion 61B (that is, the upper surface 61B1, the tip surface 61B2, and the lower surface 61B3) of the protrusion 61 that functions centrally as the counter electrode has an uneven cross-sectional shape. So that the surface area of the counter electrode is sufficiently large. Thus, by devising the shape of the extended protrusion 61B constituting the counter electrode, it is possible to ensure a wide area of the counter electrode in a limited space in the processing container 1. Also in the present embodiment, the counter electrode surface area exposed in the plasma generation space S suppresses the oscillation of the plasma potential to generate a stable plasma in the processing vessel 1 and also causes sputtering by the plasma in the vicinity of the counter electrode. In order to weaken the action, the area ratio to the bias electrode area is preferably 1 or more, more preferably in the range of 1 to 5 and even more preferably in the range of 1 to 4. It is desirable that it is in the range of 2 or more and 4 or less. The area ratio is about 5 in the plasma processing apparatus 101 shown in FIG.

The end surface 61B2 of the projecting portion 61 which functions as a counter electrode is preferably a protrusion amount does not reach the position P WE of the peripheral edge of the wafer W mounted on the mounting table 5. The tip of the projecting portion 61 is, when the position P WE of the peripheral edge of the wafer W reaches the inner, high-density plasma region generated in the processing chamber 1 is smaller than the wafer size, the plasma density of the peripheral portion of the wafer W As a result, the uniformity of the processing content on the outer periphery of the wafer W may be adversely affected. On the other hand, the protruding portion 61 that functions as the counter electrode has a base end portion at the abutting end with the side wall 1b on the side opposite to the front end portion (the front end surface 61B2) (on the side wall 1b side of the processing vessel 1). In the form of, it is only necessary that the part B in the middle is exposed to the plasma generation space S. In other words, in the present embodiment, the exposed end of the lower surface of the contact support portion 61A of the protruding portion 61 that functions as the counter electrode is a contact point with the upper liner 49a indicated by the portion B in FIG.

  In addition, the upper surface 61B1 of the extended protrusion 61B facing the space S1 is disposed away from the lower surface of the microwave transmission plate 28. That is, the extended protrusion 61 </ b> B protrudes toward the plasma generation space S with an interval L <b> 1 from the microwave transmission plate 28. In this way, by providing the space L1 between the microwave transmission plate 28 and the extended protrusion 61B, the surface area as the counter electrode can be increased without reducing the effective area for introducing the microwave of the microwave transmission plate 28. It can be secured sufficiently wide. Further, since the space S1 becomes a part of the plasma generation space S, and plasma is generated there, the plasma processing on the wafer W can be made uniform. On the other hand, when the microwave transmission plate 28 and the extended protrusion 61B are disposed in close contact with each other without providing the interval L1, if the surface area of the counter electrode is increased in the processing container 1, the microwave transmission plate 28 is used. It is necessary to increase the amount of protrusion to the center side. Then, when the plasma is generated, the effective area of the microwave transmission plate 28 is reduced by the amount of the extended protrusion 61B, so that the amount of microwave power supplied into the processing container 1 is reduced and the plasma is not generated. Even if generated, it becomes unstable. In order to solve this, it is necessary to enlarge the processing container 1, but the installation area increases and the manufacturing cost of the apparatus also increases.

  This distance L1 is preferably larger than the thickness of the sheath between the plasma generated immediately below the microwave transmission plate 28 and the microwave transmission plate 28, and is sufficiently larger than the mean free path of electrons. Preferably there is. For example, the distance L1 is preferably in the range of 10 mm to 30 mm, and more preferably in the range of 20 mm to 25 mm. If the interval L1 is less than 10 mm, the plasma may not be stabilized because abnormal discharge occurs in the space S1, and particularly when the interval L1 is less than the sheath thickness, it is difficult to generate plasma in the processing vessel 1. There is a case. On the other hand, when the distance L1 exceeds 30 mm, the extended protrusion 61B is too close to the electrode 7 of the mounting table 5, and thus it becomes difficult to function as a counter electrode. Further, the extended protruding part 61B is thermally damaged by the heat of the mounting table 5. There is a possibility.

  Similarly, the upper limit of the thickness L2 of the extended protrusion 61B (that is, the distance between the upper surface 61B1 and the lower surface 61B3) L2 is, for example, 20 mm in order to avoid the extended protrusion 61B from being too close to the electrode 7 of the mounting table 5. It is preferable to do. However, if the thickness L2 of the extended protrusion 61B is too small, the effect as the counter electrode is reduced. Therefore, the lower limit of the thickness L2 is preferably set to 5 mm or more, for example. Therefore, the thickness L2 of the extended protrusion 61B is preferably in the range of 5 mm to 20 mm, and more preferably in the range of 7 mm to 17 mm.

  Furthermore, the distance L3 (here, the difference between the height positions of the two members) from the lower surface 61B3 of the extended protrusion 61B to the upper surface of the mounting table 5 is expanded while functioning the extended protrusion 61B as a counter electrode. In order to avoid the protrusion 61B from being too close to the electrode 7 of the mounting table 5, for example, it is preferably in the range of 15 mm to 60 mm, and more preferably in the range of 20 mm to 25 mm.

  Further, in the plasma processing apparatus 101 of the present embodiment, the gas introduction port 15a is provided in the contact support portion 61A above the extended protrusion 61B, and the space between the extended protrusion 61B and the microwave transmission plate 28 is provided. The processing gas is supplied to S1. With this configuration, it is possible to promote the replacement and discharge of the gas in the space S1 directly below the microwave transmission plate 28, which is a part of the plasma generation space S, and it is easy to activate the processing gas. As a result, plasma can be efficiently generated in the entire space S1 immediately below the microwave transmission plate 28. As another effect, when the plasma processing apparatus 101 performs, for example, a plasma nitriding process by supplying a processing gas to the space S1 directly below the microwave transmitting plate 28, the quartz gas transmitting plate 28 emits the gas. Since it is possible to promote the discharge of oxygen, it is possible to suppress a decrease in the nitrogen concentration in the formed nitride film.

  Also in the present embodiment, the protective film 48 is provided on the exposed surface of the protrusion 61. The protective film 48 prevents the protrusion 61 from being exposed to plasma and sputtered to generate metal contamination and particles. Even if the protective film 48 is formed on the protruding portion 61, the function as the counter electrode is maintained, and a stable plasma can be generated to perform a uniform plasma treatment.

  In addition, the unevenness | corrugation of the expansion protrusion part 61B is not restricted to a waveform as shown in FIG. 5, It can be set as arbitrary shapes, such as a groove shape and a hole shape, as a shape which can expand a surface area. However, from the viewpoint of preventing abnormal discharge on the surface of the extended protrusion 61B facing the plasma generation space S and preventing particle generation, a waveform having rounded corners as shown in FIG. 5 is preferable. The unevenness does not necessarily have to be formed on the entire surface of the extended protrusion 61B. For example, the unevenness can be provided only on the upper surface 61B1 or only the lower surface 61B3 of the extended protrusion 61B.

  Other configurations and effects of the present embodiment are the same as those of the first embodiment.

[Third Embodiment]
Next, a plasma processing apparatus according to a third embodiment of the present invention will be described with reference to FIG. The plasma processing apparatus 102 according to the third embodiment is the same as the plasma processing apparatus 100 according to the first embodiment except for the features thereof, and therefore the overall configuration is described (FIGS. 1 and 3A). 4) is omitted, and in FIG. 6, the same components as those in FIG.

  In the plasma processing apparatuses of the first and second embodiments, the extended protrusions 60B and 61B are provided on the protrusions 60 and 61 of the lid member 27, and the parts mainly function as counter electrodes. In the plasma processing apparatus 102, an extended protrusion 62 that protrudes inward as a part of the processing container 1 is provided on the upper part of the processing container 1, and the area of the part that functions as a counter electrode is expanded. Thus, by forming the processing container 1 and the extended protrusion 62 integrally, heat conductivity and conductivity can be ensured. The extended protrusion 62 is in partial contact with and electrically connected to the contact support portion 60 ′ that supports the microwave transmission plate 28 in the lid member 27.

  The extended protrusion 62 is provided at the upper end of the side wall 1 b of the processing container 1. The extended protrusion 62 includes an abutting portion 62A that abuts against the abutting support portion 60 'of the lid member 27, and an exposed portion 62B having an exposed upper surface 62B1, a distal end surface 62B2, and a lower surface 62B3. Both the contact support portion 60 ′ and the extended protrusion 62 are formed facing the plasma generation space S, and are paired with the electrode 7 of the mounting table 5 serving as the first electrode across the plasma generation space S. This is a main part that functions as a counter electrode (second electrode). Specifically, from the part A indicated by a circle in the drawing, which is the end of the contact part between the contact support part 60 ′ of the lid member 27 and the microwave transmitting plate 28 in FIG. 6, the contact support part 60 ′. In the drawing, it is the end of the exposed lower surface of the extended protrusion 62 that bypasses the exposed surface of the extended protrusion 62 and the surface of the extended protrusion 62 (that is, the exposed upper surface 62B1, the distal end surface 62B2, and the lower surface 62B3 of the extended protrusion 62). The inner peripheral surface that reaches the part B indicated by a circle (the contact end with the upper liner 49a) is a part that functions as a counter electrode. In the present embodiment, the surface from the part A to the part B is exposed to the plasma generation space S to form an annular counter electrode. Thus, the counter electrode can be formed by a plurality of members (the lid member 27 and the processing container 1) having a surface facing the plasma generation space S. Then, by providing an annular member mainly serving as a counter electrode so as to protrude into the plasma generation space, it is difficult to dispose the counter electrode at a position directly above the mounting table 5 because the microwave transmitting plate 28 is provided. Also in the RLSA type microwave plasma processing apparatus 102, a sufficiently large surface area of the counter electrode can be secured. Further, in the present embodiment, since the extended protrusions 62 that should be called extended portions of the counter electrode are provided on the upper portion of the processing container 1, the microwave transmitting plate 28 is formed from the surface of the wafer W placed on the mounting table 5. This is effective when it is desired to reduce the distance (gap G; see FIG. 1).

  Also in the present embodiment, the counter electrode surface area exposed in the plasma generation space S suppresses the oscillation of the plasma potential to generate a stable plasma in the processing vessel 1 and also causes sputtering by the plasma in the vicinity of the counter electrode. In order to weaken the action, the area ratio to the bias electrode area is preferably 1 or more, more preferably in the range of 1 to 5 and even more preferably in the range of 1 to 4. It is desirable that it is in the range of 2 or more and 4 or less.

The end surface 62B2 of the extended projection 62 which functions as a counter electrode is preferably a protrusion amount does not reach the position P WE of the peripheral edge of the wafer W mounted on the mounting table 5. The tip of the extended projection 62 is, when the position P WE of the peripheral edge of the wafer W reaches the inner, high-density plasma region generated in the processing chamber 1 is smaller than the wafer size, the plasma density of the peripheral portion of the wafer W May decrease, and the uniformity of processing contents on the outer periphery of the wafer W may be adversely affected. On the other hand, the extended protrusion 62 functioning as a counter electrode has a corner portion bent from the side wall 1b on the side opposite to the front end portion (the front end surface 62B2) (on the side wall 1b side of the processing vessel 1). In this embodiment, it suffices that the portion B in the middle is exposed to the plasma generation space S. That is, in the present embodiment, the exposed end of the lower surface of the extended protrusion 62 that functions as a counter electrode is a contact point with the upper liner 49a indicated by the portion B in FIG.

  Further, the upper surface 62B1 of the extended protrusion 62 that faces the space S1 is disposed away from the lower surface of the microwave transmission plate 28. That is, the extended protrusion 62 protrudes toward the plasma generation space S with a gap L1 from the microwave transmission plate 28. In this way, by providing the space L1 between the microwave transmitting plate 28 and the extended protrusion 62, the surface area as the counter electrode can be increased without reducing the effective area for introducing the microwave of the microwave transmitting plate 28. It can be secured sufficiently wide. Further, since the space S1 becomes a part of the plasma generation space S, and plasma is generated there, the plasma processing on the wafer W can be made uniform. On the other hand, when the microwave transmission plate 28 and the extended protrusion 62 are disposed in close contact with each other without providing the interval L1, if the surface area of the counter electrode is increased in the processing container 1, the microwave transmission plate 28 is used. It is necessary to increase the amount of protrusion to the center side. Then, when generating plasma, the effective area of the microwave transmission plate 28 is reduced by the contact area with the upper surface 62B1 of the extended protrusion 62, and the supply amount of microwave power into the processing container 1 is reduced. Plasma is not generated or is unstable even if generated. In order to solve this, it is necessary to enlarge the processing container 1, but the installation area increases and the manufacturing cost of the apparatus also increases.

  The interval L1 is preferably larger than the thickness of the sheath between the plasma generated immediately below the microwave transmitting plate 28 and the microwave transmitting plate 28. For example, the interval L1 is in the range of 10 mm to 30 mm. Is preferable, and it is more preferable to set it within the range of 20 mm or more and 25 mm or less. If the interval L1 is less than 10 mm, the plasma may not be stabilized because abnormal discharge occurs in the space S1, and particularly when the interval L1 is less than the sheath thickness, it is difficult to generate plasma in the processing vessel 1. There is a case. On the other hand, if the distance L1 exceeds 30 mm, the extended protrusion 62 is too close to the electrode 7 of the mounting table 5, so that it becomes difficult to function as a counter electrode, and the extended protruding portion 62 is thermally damaged by the heat of the mounting table 5. There is a possibility.

  Similarly, the upper limit of the thickness L2 of the extended protrusion 62 (that is, the distance between the upper surface 62B1 and the lower surface 62B3) L2 is, for example, 20 mm in order to prevent the extended protrusion 62 from being too close to the electrode 7 of the mounting table 5. It is preferable to do. However, if the thickness L2 of the extended protrusion 62 is too small, the effect as the counter electrode is reduced. Therefore, the lower limit of the thickness L2 is preferably set to 5 mm, for example. Therefore, the thickness L2 of the extended protrusion 62 is preferably in the range of 5 mm to 20 mm, and more preferably in the range of 7 mm to 17 mm.

  Furthermore, the distance L3 (here, the difference in height position between the two members) from the lower surface 62B3 of the extended protrusion 62 to the upper surface of the mounting table 5 is expanded while functioning the extended protrusion 62 as a counter electrode. In order to avoid the protrusion 62 from being too close to the electrode 7 of the mounting table 5, for example, it is preferably in the range of 15 mm to 60 mm, and more preferably in the range of 20 mm to 25 mm.

  Further, in the plasma processing apparatus 102 of the present embodiment, the gas introduction port 15a is provided in the contact support portion 60 ′ located above the extended protrusion 62, and between the extended protrusion 62 and the microwave transmission plate 28. The processing gas is supplied to the space S1. With this configuration, it is possible to promote the replacement and discharge of the gas in the space S1 directly below the microwave transmission plate 28, which is a part of the plasma generation space S, and it is easy to activate the processing gas. As a result, plasma can be efficiently generated in the entire space S1 immediately below the microwave transmission plate 28. As another effect, when a plasma nitriding process is performed in the plasma processing apparatus 102 by supplying a processing gas to the space S1 immediately below the microwave transmitting plate 28, the gas is emitted from the quartz microwave transmitting plate 28 made of quartz. Since it is possible to promote the discharge of oxygen, it is possible to suppress a decrease in the nitrogen concentration in the formed nitride film.

  In the plasma processing apparatus 102 of the present embodiment, the protective film 48 is provided on the surfaces of the contact support portion 60 ′ and the extended protrusion 62 that constitute the counter electrode. That is, as shown in FIG. 6, a protective film 48 is coated on the exposed surface exposed to plasma of the abutting support portion 60 ′ of the aluminum lid member 27. Further, a protective film 48 is also coated on the exposed surface of the extended protrusion 62 provided in the processing container 1 that is exposed to plasma. The protective film 48 prevents the contact support portion 60 ′ and the extended protrusion 62 from being exposed to plasma and sputtered to generate metal contamination and particles. Even if the protective film 48 is formed on the contact support portion 60 ′ and the extended protrusion portion 62, the function as the counter electrode is maintained, and stable plasma is generated and uniform plasma processing is possible.

  Other configurations and effects of the present embodiment are the same as those of the first embodiment.

[Fourth Embodiment]
Next, a plasma processing apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. The plasma processing apparatus 103 according to the fourth embodiment is the same as that of the first embodiment except for the features thereof, and therefore the overall configuration (FIGS. 1, 3A, and 4) will be described. In FIG. 7, the same components as those in FIG. 2A are denoted by the same reference numerals and description thereof is omitted.

  In the plasma processing apparatus 103 according to the present embodiment, an extended protrusion 63 is provided on the contact support portion 60 ′ of the lid member 27 by additionally attaching an annular auxiliary electrode member in a detachable manner. In this way, part or all of the counter electrode may be formed by mounting an additional member. By making the extended protrusion 63 a separate member from the lid member 27 and the processing container 1, it can be easily replaced as a consumable item. The extended protrusion 63 has an upper surface 63a, a tip surface 63b, and a lower surface 63c.

  The auxiliary electrode member constituting the extended protrusion 63 is not particularly limited as long as it is a conductor. For example, silicon or the like can be used in addition to a metal material such as aluminum or an alloy thereof, or stainless steel. In particular, when the extended protrusion 63 is formed of silicon, it is advantageous because it is not necessary to provide a protective film on the surface. The extended protrusion 63 can be fixed to the inner peripheral surface of the contact support portion 60 ′ of the lid member 27 by an arbitrary fixing direction such as a screw (not shown).

  In the plasma processing apparatus 103 of the present embodiment, the extended protrusion 63 is formed facing the plasma generation space S, and separates the plasma generation space S from the electrode 7 of the mounting table 5 that is the first electrode. It is a main part that functions as a counter electrode (second electrode) that makes a pair. Specifically, the contact support portion 60 ′ from the portion A indicated by a circle in the drawing, which is the end of the contact portion between the contact support portion 60 ′ of the lid member 27 and the microwave transmitting plate 28 in FIG. 7. In the figure, the exposed surface and the surface of the extended protrusion 63 (that is, the exposed upper surface 63a, the distal end surface 63b, and the lower surface 63c of the extended protrusion 63) are bypassed and the end of the exposed lower surface of the contact support portion 60 ′ is shown. The inner peripheral surface that reaches the part B indicated by a circle is a part that functions as a counter electrode. In the present embodiment, the surface from the part A to the part B is exposed to the plasma generation space S to form an annular counter electrode. As described above, the counter electrode can be formed by a plurality of members (auxiliary electrode members of the lid member 27 and the extended protrusion 63) having a surface facing the plasma generation space S. Then, by providing an annular member mainly serving as a counter electrode so as to protrude into the plasma generation space S, it is difficult to deploy the counter electrode at a position directly above the mounting table 5 because the microwave transmitting plate 28 is provided. Even in the RLSA type microwave plasma processing apparatus 103, a sufficiently large surface area of the counter electrode can be secured.

  In the present embodiment, the expansion protrusion 63 is additionally attached to the contact support portion 60 ′ of the lid member 27, so that a sufficient surface area of the portion functioning as the counter electrode can be secured. In this way, by configuring the counter electrode by combining a plurality of members, the area of the counter electrode can be secured with a sufficient width in a limited space in the processing container 1. Also in the present embodiment, the counter electrode surface area exposed in the plasma generation space S suppresses the oscillation of the plasma potential to generate a stable plasma in the processing vessel 1 and also causes sputtering by the plasma in the vicinity of the counter electrode. In order to weaken the action, the area ratio to the bias electrode area is preferably 1 or more, more preferably in the range of 1 to 5 and even more preferably in the range of 1 to 4. It is desirable that it is in the range of 2 or more and 4 or less.

In addition, it is preferable that the distal end portion (front end surface 63 b) of the extended projecting portion 63 that functions as a counter electrode has a projecting length that does not reach the position PWE of the peripheral edge of the wafer W placed on the mounting table 5. The tip of the extended protrusion 63 is, when the position P WE of the peripheral edge of the wafer W reaches the inner, high-density plasma region generated in the processing chamber 1 is smaller than the wafer size, the plasma density of the peripheral portion of the wafer W May decrease, and the uniformity of processing contents on the outer periphery of the wafer W may be adversely affected. On the other hand, on the side opposite to the distal end portion (front end surface 63b) of the extended protrusion 63, the region B is exposed to the plasma generation space S beyond the joint portion between the extended protrusion 63 and the contact support portion 60 ′. ing. In other words, in the present embodiment, the exposed end of the lower surface of the contact support portion 60 ′ functioning as the counter electrode is a contact point with the upper liner 49 a indicated by the portion B in FIG.

  Further, the upper surface 63 a of the extended protrusion 63 is disposed away from the lower surface of the microwave transmission plate 28. That is, the extended protrusion 63 protrudes toward the plasma generation space S with a gap L1 from the microwave transmission plate 28. In this way, by providing the space L1 between the microwave transmission plate 28 and the extended protrusion 63, the surface area as the counter electrode can be increased without reducing the effective area for introducing the microwave of the microwave transmission plate 28. It can be secured sufficiently wide. Further, since the space S1 becomes a part of the plasma generation space S, and plasma is generated there, the plasma processing on the wafer W can be made uniform. On the other hand, when the microwave transmission plate 28 and the extended protrusion 63 are disposed in close contact with each other without providing the interval L1, if the surface area of the counter electrode is increased in the processing container 1, the microwave transmission plate 28 is used. It is necessary to increase the amount of protrusion to the center side. Then, when the plasma is generated, the effective area of the microwave transmission plate 28 is reduced by the contact area with the upper surface 63a of the extended protrusion 63, and the supply amount of the microwave power into the processing container 1 is reduced. Plasma is not generated or is unstable even if generated. In order to solve this, it is necessary to enlarge the processing container 1, but the installation area increases and the manufacturing cost of the apparatus also increases.

  The interval L1 is preferably larger than the thickness of the sheath between the plasma generated immediately below the microwave transmitting plate 28 and the microwave transmitting plate 28. For example, the interval L1 is in the range of 10 mm to 30 mm. Is preferable, and it is more preferable to set it within the range of 20 mm or more and 25 mm or less. If the interval L1 is less than 10 mm, the plasma may not be stabilized because abnormal discharge occurs in the space S1, and particularly when the interval L1 is less than the sheath thickness, it is difficult to generate plasma in the processing vessel 1. There is a case. On the other hand, if the distance L1 exceeds 30 mm, the extended protrusion 63 is too close to the electrode 7 of the mounting table 5, so that it becomes difficult to function as a counter electrode, and the extended protruding portion 63 is thermally damaged by the heat of the mounting table 5. There is a possibility.

  Similarly, the upper limit of the thickness L2 of the extended protrusion 63 (that is, the distance between the upper surface 63a and the lower surface 63c) L2 is, for example, 20 mm in order to prevent the extended protrusion 63 from being too close to the electrode 7 of the mounting table 5. It is preferable to do. However, if the thickness L2 of the extended protrusion 63 is too small, the effect as the counter electrode is lowered. Therefore, the lower limit of the thickness L2 is preferably set to 5 mm, for example. Therefore, the thickness L2 of the extended protrusion 63 is preferably in the range of 5 mm to 20 mm, and more preferably in the range of 7 mm to 17 mm.

  Furthermore, the distance L3 from the lower surface 63c of the extended protrusion 63 to the upper surface of the mounting table 5 (which means a difference in height position between the two members) is as described above while the extended protrusion 63 functions as a counter electrode. Similarly, in order to avoid the extended protrusion 63 from being too close to the electrode 7 of the mounting table 5, for example, it is preferably in the range of 15 mm to 60 mm, and more preferably in the range of 20 mm to 25 mm.

  Further, in the plasma processing apparatus 103 according to the present embodiment, the gas introduction port 15a is provided in the abutting support portion 60 ′ located above the extended protrusion 63, and between the extended protrusion 63 and the microwave transmission plate 28. The processing gas is supplied to the space S1. With this configuration, it is possible to promote the replacement and discharge of the gas in the space S1 directly below the microwave transmission plate 28, which is a part of the plasma generation space S, and it is easy to activate the processing gas. As a result, plasma can be efficiently generated in the entire space S1 immediately below the microwave transmission plate 28. As another effect, when a plasma nitriding process is performed in the plasma processing apparatus 103 by supplying a processing gas to the space S1 immediately below the microwave transmitting plate 28, the gas is emitted from the quartz microwave transmitting plate 28 made of quartz. Since it is possible to promote the discharge of oxygen, it is possible to suppress a decrease in the nitrogen concentration in the formed nitride film.

  Note that the shape of the extended protrusion 63 is not limited to the cross-sectional shape as shown in FIG. 7, and may be a shape that can increase the surface area, for example, an L-shaped cross-section, or a shape that has irregularities or grooves on the surface. It can be of any shape. However, from the viewpoint of preventing abnormal discharge on the surface of the extended protrusion 63 facing the plasma generation space S and preventing the generation of particles, it is preferable to have a rounded corner as shown in FIG. Also in the present embodiment, the protective film 48 is provided on the exposed surfaces of the contact support portion 60 ′ and the extended protrusion 63 facing the plasma generation space S. The protective film 48 prevents the contact support portion 60 ′ and the extended protrusion 63 from being exposed to plasma and sputtered to generate metal contamination and particles. Even if the protective film 48 is formed on the contact support portion 60 ′ and the extended protrusion 63, the function as the counter electrode is maintained, and stable plasma can be generated to perform uniform plasma processing. Note that when the entire extended protrusion 63 is formed of silicon, the protective film may not be provided.

  Other configurations and effects of the present embodiment are the same as those of the first embodiment.

[Fifth Embodiment]
Next, a plasma processing apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. The plasma processing apparatus 104 of the fifth embodiment is the same as that of the first embodiment except for the features thereof, and therefore the overall configuration (FIGS. 1, 3A, and 4) will be described. In FIG. 8, the same components as those in FIG. 2A are denoted by the same reference numerals, and description thereof is omitted.

  In the plasma processing apparatus 103 of the fourth embodiment, the extended protrusion 63 (auxiliary electrode member) is attached to the lid member 27. However, in the plasma processing apparatus 104 of the present embodiment, the extended protrusion 64 (annular auxiliary member). An electrode member) is detachably attached to the upper portion of the processing container 1. In this way, part or all of the counter electrode may be formed by mounting an additional member. By making the extended protrusion 64 a separate member from the lid member 27 and the processing container 1, it can be easily replaced as a consumable item. The extended protrusion 64 has an upper surface 64a, a tip surface 64b, and a lower surface 64c. On the upper surface 64 a of the extended protrusion 64, a step is provided in accordance with the shape of the contact support portion 60 ′ of the lid member 27. Further, the lower surface 64c of the extended protrusion 64 has a plurality (double in FIG. 8) of annular grooves 64d.

  The extended protrusion 64 is not particularly limited as long as it is a conductor. For example, silicon or the like can be used in addition to a metal material such as aluminum or an alloy thereof, or stainless steel. When the extended protrusion 64 is formed of silicon, there is no need to provide a protective film on the surface, which is advantageous. The extended protrusion 64 can be fixed to the inner surface of the side wall 1b of the processing container 1 by an arbitrary fixing direction such as a screw (not shown).

  In the plasma processing apparatus 104 of the present embodiment, the extended protrusion 64 is formed facing the plasma generation space S and separates the plasma generation space S from the electrode 7 of the mounting table 5 that is the first electrode. It is a main part that functions as a counter electrode (second electrode) that makes a pair. Specifically, the contact support portion 60 ′ from the portion A indicated by a circle in the drawing, which is the end of the contact portion between the contact support portion 60 ′ of the lid member 27 and the microwave transmitting plate 28 in FIG. 8. The exposed surface and the surface of the extended protrusion 64 (that is, the upper surface 64a, the front end surface 64b, and the lower surface 64c of the extended protrusion 64) are shown in circles in the drawing, which are the ends of the exposed lower surface of the extended protrusion 64. The inner peripheral surface that reaches the part B is a part that functions as a counter electrode. In the present embodiment, the surface from the part A to the part B is exposed to the plasma generation space S to form an annular counter electrode. Thus, the counter electrode can be formed by a plurality of members (the lid member 27 and the extended protrusion 64) having a surface facing the plasma generation space S. Then, by providing an annular member mainly serving as a counter electrode so as to protrude into the plasma generation space, it is difficult to dispose the counter electrode at a position directly above the mounting table 5 because the microwave transmitting plate 28 is provided. Also in the RLSA type microwave plasma processing apparatus 104, a sufficiently large surface area of the counter electrode can be secured.

  In the present embodiment, the expansion protrusion 64 is additionally attached to the contact support portion 60 ′ of the lid member 27, so that a sufficient surface area of the portion functioning as the counter electrode can be secured. As described above, by configuring the counter electrode by combining a plurality of members, the area of the counter electrode can be secured in a limited space in the processing container 1. Also in the present embodiment, the counter electrode surface area exposed in the plasma generation space S suppresses the oscillation of the plasma potential to generate a stable plasma in the processing vessel 1 and also causes sputtering by the plasma in the vicinity of the counter electrode. In order to weaken the action, the area ratio to the bias electrode area is preferably 1 or more, more preferably in the range of 1 to 5 and even more preferably in the range of 1 to 4. It is desirable that it is in the range of 2 or more and 4 or less.

Moreover, it is preferable that the distal end portion (front end surface 64 b) of the extended projecting portion 64 that functions as a counter electrode has a projecting length that does not reach the position PWE of the peripheral edge of the wafer W placed on the mounting table 5. The tip of the extended projection 64 is, when the position P WE of the peripheral edge of the wafer W reaches the inner, high-density plasma region generated in the processing chamber 1 is smaller than the wafer size, the plasma density of the peripheral portion of the wafer W May decrease, and the uniformity of processing contents on the outer periphery of the wafer W may be adversely affected. On the other hand, on the side opposite to the distal end portion (the distal end surface 64b) of the extended protrusion 64, the abutting end with the side wall 1b is the base end portion of the extended protrusion 64. Up to a certain part B is exposed to the plasma generation space S. In other words, in the present embodiment, the exposed end of the lower surface 64c of the extended protrusion 64 that functions as a counter electrode is a contact point with the upper liner 49a indicated by the portion B in FIG.

  Further, the upper surface 64 a of the extended protrusion 64 is disposed away from the lower surface of the microwave transmission plate 28. That is, the extended protrusion 64 protrudes toward the plasma generation space S with a gap L1 from the microwave transmission plate 28. In this way, by providing the gap L1 between the microwave transmission plate 28 and the extended protrusion 64, the surface area of the counter electrode can be sufficiently increased without reducing the effective area for introducing the microwave of the microwave transmission plate 28. Can be secured widely. Further, since the space S1 becomes a part of the plasma generation space S, and plasma is generated there, the plasma processing on the wafer W can be made uniform. On the other hand, when the microwave transmitting plate 28 and the extended protrusion 64 are disposed in close contact with each other without providing the interval L1, if the surface area of the counter electrode is increased in the processing container 1, the microwave transmitting plate 28 is used. It is necessary to increase the amount of protrusion to the center side. Then, when the plasma is generated, the effective area of the microwave transmission plate 28 is reduced by the contact area with the upper surface 64a of the extended protrusion 64, and the supply amount of the microwave power into the processing container 1 is reduced. Plasma is not generated or is unstable even if generated. In order to solve this, it is necessary to enlarge the processing container 1, but the installation area increases and the manufacturing cost of the apparatus also increases.

  The interval L1 is preferably larger than the thickness of the sheath between the plasma generated immediately below the microwave transmitting plate 28 and the microwave transmitting plate 28. For example, the interval L1 is in the range of 10 mm to 30 mm. Is preferable, and it is more preferable to set it within the range of 20 mm or more and 25 mm or less. When the distance L1 is less than 10 mm, the plasma may not be stabilized. In particular, when the distance L1 is equal to or less than the sheath thickness, it may be difficult to generate plasma in the processing container 1. On the other hand, if the distance L1 exceeds 30 mm, the extended protrusion 64 is too close to the electrode 7 of the mounting table 5, so that it becomes difficult to function as a counter electrode, and the extended protruding portion 64 is thermally damaged by the heat of the mounting table 5. There is a possibility.

  Similarly, in order to avoid that the extended protrusion 64 is too close to the electrode 7 of the mounting table 5, the upper limit of the thickness of the extended protrusion 64 (here, the distance between the upper surface 64a and the lower end of the lower surface 64c) L2 is For example, it is preferably 20 mm. However, if the thickness L2 of the extended protrusion 64 is too small, the effect as the counter electrode is reduced. Therefore, the lower limit of the thickness L2 is preferably set to 5 mm or more, for example. Therefore, the thickness L2 of the extended protrusion 64 is preferably in the range of 5 mm to 20 mm, and more preferably in the range of 7 mm to 17 mm. The depth of the groove 64d is arbitrary.

  Furthermore, the distance L3 (here, the difference in height position between both members) from the lower end of the lower surface 64c of the extended protrusion 64 to the upper surface of the mounting table 5 is such that the extended protrusion 64 functions as a counter electrode. In the same manner as described above, in order to avoid the extended protrusion 64 from being too close to the electrode 7 of the mounting table 5, it is preferable to be within a range of, for example, 15 mm to 60 mm, and more preferably within a range of 20 mm to 25 mm. preferable.

  Further, in the plasma processing apparatus 104 of the present embodiment, the gas introduction port 15a is provided in the abutting support portion 60 ′ located above the extended protrusion 64, and between the extended protrusion 64 and the microwave transmission plate 28. The processing gas is supplied to the space S1. With this configuration, it is possible to promote the replacement and discharge of the gas in the space S1 directly below the microwave transmission plate 28, which is a part of the plasma generation space S, and it is easy to activate the processing gas. As a result, plasma can be efficiently generated in the entire space S1 immediately below the microwave transmission plate 28. Further, as a secondary effect, when a plasma gas nitriding process is performed in the plasma processing apparatus 104 by supplying a processing gas to the space S1 directly below the microwave transmitting plate 28, the quartz microwave transmitting plate 28 is made. Since discharge of oxygen released from the gas can be promoted, a decrease in nitrogen concentration in the nitride film to be formed can be suppressed.

  8 has double annular grooves 64d on the lower surface 64c in order to secure the surface area, the shape capable of expanding the surface area is limited to the cross-sectional shape as shown in FIG. It is not a thing. The shape of the extended protrusion 64 can be an arbitrary shape such as an annular shape or a shape in which a plurality of holes are formed in an arbitrary arrangement. However, from the viewpoint of preventing abnormal discharge on the surface of the extended projecting portion 64 facing the plasma generation space S and preventing the generation of particles, it is preferable to have a rounded corner as shown in FIG. In FIG. 8, the extended protrusion 64 is brought into contact with the contact support portion 60 ′ of the lid member 27, but may be provided apart from the contact support portion 60 ′.

In the present embodiment, the protective film 48 is provided on the exposed surface facing the plasma generation space S of the contact support portion 60 ′. On the other hand, the extended protrusion 64 is formed entirely of silicon, for example, and is not provided with a protective film. However, when the extended protrusion 64 is formed of a metal material such as aluminum, a protective film can be provided, for example, by coating a SiO 2 film on the surface thereof by plasma spraying. Even if the protective film 48 is formed, the function as the counter electrode is maintained, and stable plasma is generated and uniform plasma treatment is possible.

  Other configurations and effects of the present embodiment are the same as those of the first embodiment.

  The characteristic configurations described in the first to fifth embodiments can be combined with each other. For example, the extension protrusion 60B in the first embodiment (FIGS. 1, 2A, and 2B) and the extension protrusion 62 in the third embodiment (FIG. 6) are as in the second embodiment. The surface area may be further increased by providing irregularities on the surface. Similarly, in the extended protrusions 63 and 64 of the fourth embodiment (FIG. 7) and the fifth embodiment (FIG. 8), the surface area is further increased by providing irregularities as in the second embodiment. It may be enlarged.

  Further, both the lid member 27 and the processing container 1 may be provided with a protruding portion that functions as a counter electrode, and both the lid member 27 and the processing container 1 may be provided with an auxiliary electrode member (an extended protruding portion) that functions as a counter electrode. 63, 64) may be provided.

  Next, the effect of this invention is demonstrated based on an experimental result. In the plasma processing apparatus having the same configuration as that of the plasma processing apparatus 100 of FIG. 1, when the potential of the mounting table 5 is measured when a high frequency voltage is applied to the electrode 7 of the mounting table 5, as schematically shown in FIGS. 9A and 9B. AC waveform is generated. FIG. 9A shows a case where the counter electrode surface area is insufficient with respect to the bias electrode area, and FIG. 9B shows a case where the counter electrode surface area is sufficiently large with respect to the bias electrode area. ing. Vmax in the figure is the maximum value of the amplitude of the high-frequency voltage of the mounting table 5, and it is generally considered that the potential difference of Vmax−GND (ground potential) corresponds to the amplitude of vibration of the plasma potential (Vp). . In FIG. 9A where the counter electrode surface area is insufficient with respect to the bias electrode area, Vp vibrates due to the high frequency, and Vmax increases. On the other hand, in FIG. 9B in which the surface area of the counter electrode is sufficiently large with respect to the area of the bias electrode, it is possible to generate the self-bias (Vdc) with almost no change in the plasma potential.

Next, FIG. 10 shows the results of investigating the relationship between the amount of aluminum (Al) contamination generated when plasma oxidation is performed under different processing conditions and Vmax in the plasma processing apparatus. The processing conditions are as follows. The treatment pressure was 6.67 Pa, 20 Pa, or 40 Pa. Ar gas and O 2 gas were used as the processing gas, and the flow rate ratio of the oxygen gas in the processing gas was 0.5 vol%, 1 vol%, 25 vol%, or 50 vol%. The frequency of the high frequency power for bias supplied to the electrode 7 of the mounting table 5 was 13.56 MHz, and the high frequency power was 450 W, 600 W, or 900 W. From FIG. 10, regardless of the processing conditions, when Vmax increases, Al contamination increases in direct proportion. It is considered that the Al contamination is caused by the fact that the Al lid member 27 is sputtered. In order to suppress Al contamination, it is effective to reduce the value of Vmax. For example, in order to suppress Al contamination to 7 × 10 10 [atoms / cm 2 ] or less, Vmax may be set to 70 V or less. It is understood. In order to suppress Vmax, as shown in FIG. 9B, it is effective to make the counter electrode surface area larger than the bias electrode area.

  Therefore, an experiment was conducted to examine the change in Vmax when the bias electrode area was made constant and the counter electrode surface area was changed. 11 to 16 show the counter electrode area ratio (horizontal axis) and Vmax (vertical axis) when plasma oxidation is performed under various processing conditions in the plasma processing apparatus having the same configuration as the plasma processing apparatus 100 of FIG. ). Here, the counter electrode area ratio means a value obtained by dividing the counter electrode surface area by the bias electrode area. Ar gas and oxygen gas were used as the processing gas. The frequency of the high frequency power for bias supplied to the electrode 7 of the mounting table 5 was 13.56 MHz, and the high frequency power was 0 W (not applied), 300 W, 450 W, 600 W, or 900 W.

FIG. 11 shows the experimental results under the conditions where the processing pressure is 6.67 Pa, the oxygen gas flow rate ratio is 0.5 vol%, and the microwave power for generating plasma is set to 1200 W. FIG. 12 shows the experimental results under conditions where the processing pressure is 6.67 Pa, the oxygen gas flow rate ratio is 50 vol%, and the microwave power is set to 3400 W. FIG. 13 shows experimental results under conditions where the processing pressure is 20 Pa, the oxygen gas flow rate ratio is 0.5 vol%, and the microwave power is set to 1200 W. FIG. 14 shows the experimental results under conditions where the processing pressure is 20 Pa, the oxygen gas flow rate ratio is 50 vol%, and the microwave power is set to 3400 W. FIG. 15 shows the experimental results under conditions where the processing pressure is 40 Pa, the oxygen gas flow rate ratio is 0.5 vol%, and the microwave power is set to 1200 W. FIG. 16 shows experimental results under conditions where the processing pressure is 40 Pa, the oxygen gas flow rate ratio is 50 vol%, and the microwave power is set to 3400 W. Counter electrode surface area, 500cm 2, 1400cm 2, 1800cm 2, 2200cm 2, or a 3150 cm 2, the bias electrode area was set to 855cm 2.

  It can be seen from the graphs of FIGS. 11 to 16 that Vmax decreases as the counter electrode area ratio increases. This tendency is most noticeable when the processing pressure is 6.67 Pa, and it has been found that the lower the pressure, the greater the effect of suppressing Vmax by increasing the counter electrode area ratio. In the plasma processing apparatus having the same configuration as the plasma processing apparatus 100 of FIG. 1, in order to reliably obtain the effect of suppressing Vmax by increasing the counter electrode area ratio, it is necessary to perform the plasma processing at a processing pressure of 40 Pa or less. It is considered preferable.

Based on the above results, the amount of aluminum (Al) contamination generated when the plasma oxidation treatment was performed while changing the surface area of the counter electrode in the plasma treatment device having the same configuration as the plasma treatment device 100 of FIG. 1 was examined. . In this experiment, the counter electrode surface area was 2200 cm 2 (area ratio: large), 1800 cm 2 (area ratio: medium), 500 cm 2 (area ratio: small), and the bias electrode area was 855 cm 2 . The processing pressure was set to different pressure conditions in the range of 6.67 Pa to 40 Pa. The results are shown in FIG. In addition, the notations such as “5.0E10” and “1.8E11” in FIG. 17 indicate that the amount of Al contamination is “5.0 × 10 10 pieces” and “1.8 × 10 11 pieces”, respectively. Means that. From this result, when the counter electrode surface area is 2200 cm 2 (area ratio: large) or 1800 cm 2 (area ratio: medium), Vmax can be suppressed to 70 V or less (see FIG. 10) at a processing pressure of 40 Pa or less. The Al contamination is also sufficiently suppressed. However, when the surface area of the counter electrode is 500 cm 2 (area ratio: small), Vmax cannot be suppressed to 70 V or less (see FIG. 10) at a processing pressure of 20 Pa or less, and Al contamination is greatly increased. ing. From this result, in order to suppress Vmax to 70 V or less, it is effective to set the counter electrode surface area to 1800 cm 2 (area ratio: medium) or more. Therefore, the counter electrode area ratio (counter electrode surface area / bias electrode area) is preferably 1 or more and 5 or less, more preferably 2 or more and 5 or less, and preferably 2 or more and 4 or less. .

  Next, in a plasma processing apparatus having the same configuration as that of the plasma processing apparatus 100 of FIG. 1, an experiment was conducted to verify the effect due to the difference in the processing gas introduction position. In this experiment, when a processing gas is introduced from the gas inlet 15a of FIG. 1 in the plasma nitriding process (Example; embodiment of FIG. 1), a gas ring is provided in an annular shape on the side wall 1b below the protrusion 60. The amount of oxygen in the silicon nitride film was compared with the case where the processing gas was introduced (comparative example; not shown). The target of the plasma nitriding process is silicon on the surface of the 300 mm diameter wafer W. The amount of oxygen in the silicon nitride film was measured at the center and the edge of the wafer W using an X-ray photoelectron analyzer (XPS).

The plasma nitriding treatment conditions were as follows, and the N 2 flow rate ratio, the treatment pressure, and the high frequency bias power were changed.
<N 2 flow rate ratio 17%>
N 2 flow rate: 333 mL / min (sccm), Ar flow rate: 1667 mL / min (sccm)
<N 2 flow rate ratio 40%>
N 2 flow rate: 800 mL / min (sccm), Ar flow rate: 1200 mL / min (sccm)
Processing pressure: 6.67 Pa, 20 Pa, or 133 Pa
Microwave power: 1500W
High frequency bias power: 0 W (not applied), 450 W, or 900 W
Processing time: 90 seconds

  FIG. 18A shows the measurement result of the oxygen amount in the silicon nitride film at the center portion of the wafer W, and FIG. 18B shows the measurement result of the oxygen amount in the silicon nitride film at the edge portion of the wafer W. In the embodiment in which the processing gas is introduced from the gas inlet 15a, the oxygen in the silicon nitride film is within the range of the processing pressure of 6.67 Pa to 133 Pa as compared with the comparative example in which the processing gas is introduced from the position below the protrusion 60. It was confirmed that the concentration was lowered. The decrease in the oxygen concentration in the example was recognized regardless of whether or not the high-frequency bias was applied, and showed the same tendency at the center portion and the edge portion of the wafer W. From the measurement result of the wafer W edge portion with a processing pressure of 133 Pa originally having a high oxygen concentration, it was confirmed that the oxygen concentration was reduced by as much as about 8% in the example as compared with the comparative example.

  In the plasma processing apparatus having the same configuration as that of FIG. 1 provided with the extended protrusion 60B in order to expand the counter electrode area, the closed space S1 between the extended protrusion 60B and the microwave transmission plate 28 is a gas reservoir. Therefore, it tends to cause oxygen contamination in the silicon nitride film during the plasma nitriding process. Oxygen mixing is a phenomenon in which oxygen existing in the microwave transmission plate 28 is released into the plasma generation space S by the action of plasma and mixed into the silicon nitride film formed by plasma nitriding. In the comparative example, since the processing gas is introduced from a position below the projecting portion 60, the gas stays in the space S <b> 1 directly below the microwave transmission plate 28. As a result, oxygen released from the microwave transmitting plate 28 stays in the space S1 for a long time, and is difficult to be discharged from the processing container 1, and the probability of oxygen being mixed into the silicon nitride film on the surface of the wafer W is increased. It is thought that. On the other hand, in the embodiment, by introducing the processing gas from the gas inlet 15a into the space S1 directly below the microwave transmission plate 28, the oxygen discharged from the microwave transmission plate 28 can be quickly moved from the space S1. it can. As a result, oxygen can be efficiently discharged out of the processing container 1, so that it is considered that oxygen contamination into the silicon nitride film on the wafer W can be reduced.

  As described above in detail, the plasma processing apparatus according to each embodiment of the present invention has a space L1 between the processing container 1 or the lid member 27 and the microwave transmission plate 28 toward the plasma generation space S. Since it has the extended protrusions 60B, 61B, 62, 63, 64 that constitute at least a part of the opposing electrode that protrudes and forms a pair with the electrode 7 across the plasma generation space S, the area of the opposing electrode is sufficient. It is ensured and the vibration of the plasma potential (Vp) can be suppressed. Further, by increasing the area of the counter electrode, it is possible to suppress the surface of the counter electrode from being sputtered by the action of plasma, thereby preventing contamination. Further, by ensuring the area of the counter electrode with a sufficient area, short-circuiting and abnormal discharge in other parts can be suppressed. Furthermore, since the extended protrusions 60B, 61B, 62, 63, and 64 are provided with a space between the microwave transmission plate 28, the effective area of the microwave transmission plate 28 can be reduced without being reduced. The plasma formed in the processing container 1 can be stabilized by introducing the microwave power.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment. For example, in the above embodiment, the configuration in which the lid member 27 that supports the microwave transmission plate 28 is a part of the microwave introduction unit 26 is illustrated, but the lid member 27 that supports the microwave transmission plate 28 is a processing container. It may be a part of one.

  In the above embodiment, the gas inlet 15 a is provided in the lid member 27, but the gas inlet 15 a may be provided in a member other than the lid member 27. For example, FIG. 19 is a cross-sectional view of a principal part showing a plasma processing apparatus 102A of a modification of an aspect (third embodiment; see FIG. 6) in which an extended protrusion 62 is provided integrally with the side wall 1b of the processing container 1. is there. As shown in FIG. 19, by forming a groove-shaped annular passage 13A provided at the upper end of the side wall 1b of the processing vessel 1, and forming a gas introduction path 15b communicating with the annular passage 13A in the side wall 1b, A gas inlet 15a can be provided in the upper part of the side wall 1b. Even in this case, it is possible to supply the processing gas from the gas inlet 15 a to the space S <b> 1 between the microwave transmitting plate 28 and the extended protrusion 62.

  Further, in the above embodiment, the experimental results in the case where aluminum is used as the material of the main body of the lid member 27 as the member exposed to plasma are shown, but this is the case where other metal such as stainless steel is used. However, the same effect can be obtained.

  Further, the enlarged protrusions are not necessarily circular, and a plurality of enlarged protrusions separated from each other may have a shape protruding toward the plasma generation space S.

  Further, the content of the plasma treatment is not limited to the plasma oxidation treatment or the plasma nitridation treatment as long as it is a process for supplying high-frequency power to the electrode 7 of the mounting table 5. Plasma treatment can be targeted. Further, the object to be processed is not limited to the semiconductor wafer, but can be another substrate such as a glass substrate for FPD.

  DESCRIPTION OF SYMBOLS 1 ... Processing container, 4 ... Support part, 5 ... Mounting stand, 7 ... Electrode, 12 ... Gas supply path, 13 ... Annular passage, 15a ... Gas introduction port, 15b ... Gas introduction path, 16 ... Gas supply apparatus, 18, DESCRIPTION OF SYMBOLS 19 ... Step part, 24 ... Exhaust device, 26 ... Microwave introduction part, 27 ... Cover member, 28 ... Microwave transmission plate, 29 ... Sealing member, 31 ... Planar antenna, 32 ... Slot hole, 37 ... Waveguide, 37a ... Coaxial waveguide, 37b ... Rectangular waveguide, 39 ... Microwave generator, 40 ... Mode converter, 43 ... Matching box, 44 ... High frequency power supply, 45 ... Filter box, 46 ... Shield box, 47 ... Conductive Plate 48: Protective film 49a ... Upper liner 49b ... Lower liner 60 ... Projection part 60A ... Contact support part 60B ... Expansion projection part 100 ... Plasma processing apparatus W ... Semiconductor wafer (object to be processed)

Claims (15)

  1. A processing container having an open top for processing an object to be processed using plasma;
    A mounting table for mounting an object to be processed in the processing container;
    A first electrode embedded in the mounting table and applying a bias voltage to the object;
    A dielectric plate that closes an opening of the processing container to define a plasma generation space and transmits microwaves into the processing container;
    A planar antenna that is provided above the dielectric plate and introduces the microwave generated by a microwave generator into the processing vessel via the dielectric plate;
    The contact plate is disposed at the upper part of the processing container, has an annular shape, and has an abutment support part projecting toward the plasma generation space on the inner circumference side thereof, and the outer peripheral part of the dielectric plate on the upper surface of the contact support part A lid member for supporting
    The dielectric plate protrudes from the processing container or the abutting support portion toward the plasma generation space in the processing container with an interval, and the plasma generation space is separated from the first electrode. An annular extended protrusion that forms at least a portion of a second electrode in a pair;
    A space formed between the upper surface of the extension protrusion and the lower surface of the dielectric plate;
    Equipped with a,
    Gas introduction for introducing a processing gas into the space between the dielectric plate and the extended protrusion, and the distance between the lower surface of the dielectric plate and the upper surface of the extended protrusion is in the range of 10 mm to 30 mm A plasma processing apparatus , wherein a mouth is provided, and plasma is generated in the entire space immediately below the dielectric plate including a space between the dielectric plate and the extended protrusion .
  2. 2. The plasma processing apparatus according to claim 1 , wherein the extended protrusion is provided with a protrusion whose tip does not reach above the end of the object to be processed placed on the mounting table.
  3. The extended protrusion, plasma processing apparatus according to claim 1 or 2 are formed integrally with the lid member.
  4. The extended protrusion, plasma processing apparatus according to claim 1 or 2 are formed integrally with the processing chamber.
  5. The extended protrusion, plasma processing apparatus according to claim 1 or 2 as an auxiliary electrode member fixed to the lid member.
  6. The extended protrusion, plasma processing apparatus according to claim 1 or 2 as an auxiliary electrode member fixed to the processing container.
  7.   The plasma processing according to any one of claims 1 to 6, wherein an interval between a lower surface of the dielectric plate and a surface of the object to be processed placed on the mounting table is in a range of 50 mm or more and 150 mm or less. apparatus.
  8. The plasma processing apparatus of any one of Claim 1 to 7 with which the unevenness | corrugation is provided in the surface of the said expansion protrusion part.
  9. The area of the buried region of the first electrode surface area of the second electrode facing the plasma generation space in the mounting table, any one or more claims 1-5 within the range 8 to 1 The plasma processing apparatus according to item.
  10. The extended surface of the protruding portion, the plasma processing apparatus according to any one of claims 1, further comprising a protective film 9.
  11. The plasma processing apparatus according to claim 10 , wherein the protective film is made of silicon.
  12. The plasma processing apparatus according to any one of claims 1 to 11 , further comprising an insulating plate along an inner wall of the processing container at a position lower than a height of the mounting surface of the mounting table.
  13. The plasma processing apparatus according to claim 12 , wherein the insulating plate is formed up to a position reaching an exhaust chamber continuously provided at a lower portion of the processing container.
  14. A processing container having an open top for processing an object to be processed using plasma;
    A mounting table for mounting an object to be processed in the processing container;
    A first electrode embedded in the mounting table and applying a bias voltage to the object;
    A dielectric plate that closes an opening of the processing container to define a plasma generation space and transmits microwaves into the processing container;
    A planar antenna that is provided above the dielectric plate and introduces the microwave generated by a microwave generator into the processing vessel via the dielectric plate;
    The contact plate is disposed at the upper part of the processing container, has an annular shape, and has an abutment support part projecting toward the plasma generation space on the inner circumference side thereof, and the outer peripheral part of the dielectric plate on the upper surface of the contact support part A lid member for supporting
    The dielectric plate protrudes from the processing container or the abutting support portion toward the plasma generation space in the processing container with an interval, and the plasma generation space is separated from the first electrode. An annular extended protrusion that forms at least a portion of a second electrode in a pair;
    A space formed between the upper surface of the extension protrusion and the lower surface of the dielectric plate;
    With
    Gas introduction for introducing a processing gas into the space between the dielectric plate and the extended protrusion, and the distance between the lower surface of the dielectric plate and the upper surface of the extended protrusion is in the range of 10 mm to 30 mm A plasma processing apparatus provided with a mouth and configured to generate plasma in the entire space immediately below the dielectric plate including a space between the dielectric plate and the extended protrusion; A plasma processing method in which plasma is generated inside and an object to be processed is processed by the plasma.
  15. The plasma processing method according to claim 14 , wherein the processing pressure is 40 Pa or less.
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